All Words Glossary

Glossary of Physics Terms
beginning with letter P
Browse the Physics Glossary

parent Tweet Definition of parent Like Definition of parent on Facebook
  1. One of the two persons from whom one is immediately biologically descended; a mother or father.
  2. A person who acts as a parent in rearing a child. (adoptive parent, foster parent)
  3. (biology) An organism from which a plant or animal is immediately biologically descended.
  4. The source or origin of something.
  5. A group from which another group is formed, or which completely controls a subordinate group. (parent company)
  6. In object oriented computer programming, the object from which a child or derived object is descended The child object inherits methods and data fields from the parent.
partial vacuum Tweet Definition of partial vacuum Like Definition of partial vacuum on Facebook
  1. a region of low atmospheric pressure, especially one in which most of the air has been pumped out
particle accelerator Tweet Definition of particle accelerator Like Definition of particle accelerator on Facebook
noun (pluralparticle accelerators)
  1. A device that accelerates electrically charged particles to extremely high speeds, for the purpose of inducing high energy reactions or producing high energy radiation.
Pascal Tweet Definition of Pascal Like Definition of Pascal on Facebook
proper noun
  1. The French mathematician and physicist w:Blaise_Pascal, Blaise Pascal.
  2. The w:Pascal_programming_language, Pascal programming language.
Pascal's law Tweet Definition of Pascal Like Definition of Pascal
nounPascal"s law
  1. (physics) The law that states that a confined fluid transmits externally applied pressure uniformly in all directions; the basis of hydraulics.
(trans-top, physical law)
  • Czech: Pascal┼»v zÝíkon
Paschen-Back effect Tweet Definition of Paschen-Back effect Like Definition of Paschen-Back effect on Facebook
  1. (physics) a form of the Zeeman effect that affects the spectral lines obtained when a light source is placed in a very strong magnetic field
PC Tweet Definition of PC Like Definition of PC on Facebook
initialism (pluralPCsfor countable noun senses)
  1. (US Navy) w:Coastal Patrol, Coastal Patrol
  2. partially continuous
  3. w:Penn Central, Penn Central
  4. personal computer
    1. photocopy
  5. w:Phrozen Crew, Phrozen Crew
  6. (UK politics) w:Plaid Cymru, Plaid Cymru
  7. player character
  8. (UK, Canada) police constable
  9. politically correct
  10. political correctness
  11. polycarbonate
  12. posterior commissure
  13. w:Presbyterian Church, Presbyterian Church
  14. Privy Council
  15. privy councillor
  16. probable cause
  17. Probate Court
  18. pro-choice
  19. (TV) production code
  20. Professional Corporation
  21. (Canada) w:Progressive Canadian Party, Progressive Canadian Party
  22. (Canada, formerly) w:Progressive Conservative, Progressive Conservative
  23. progressive contextualization
  24. Proto-Celtic
  25. pubococcygeus muscle
Peltier effect Tweet Definition of Peltier effect Like Definition of Peltier effect on Facebook
  1. (Physics) a thermodynamic effect which occurs when current is passed through a thermocouple, used in computing as a cooling process
penetrometer Tweet Definition of penetrometer Like Definition of penetrometer on Facebook
  1. A mechanical device that measures the ease of penetration of an object into a semisolid
  2. A device that measures the penetrating power of electromagnetic radiation (especially X-rays)
period Tweet Definition of period Like Definition of period on Facebook
  1. (context, now mostly, North America) Punctuation mark ending a sentence or marking an abbreviation. <!-- What languages does this apply to? All? Or just most? Should it be
  1. appropriate, Appropriate for a given historical era.
    • 2004, Mark Singer, Somewhere in America, Houghton Mifflin, page 70
    • :As the guests arrived &mdash; there were about a hundred, a majority in attire &mdash; I began to feel out of place in my beige summer suit, white shirt, and red necktie. Then I got over it. I certainly didn't suffer from Confederate-uniform envy.
periodic Tweet Definition of periodic Like Definition of periodic on Facebook
  1. Relative to a period or periods.
  2. Having repeat, repeated cycle, cycles.
  3. Occurring at regular interval, intervals.
  4. Pertaining to the revolution of a celestial object in its orbit.
  5. Periodical.
phase Tweet Definition of phase Like Definition of phase on Facebook
  1. That which is exhibited to the eye; the appearance which anything manifests, especially any one among different and varying appearances of the same object.
  2. Any appearance or aspect of an object of mental apprehension or view
The problem has many phases.
  1. (astronomy) A particular appearance or state in a regularly recurring cycle of changes with respect to quantity of illumination or form, or the absence, of its enlightened disk; as, the phases of the moon or planets. Illustrated in W:Lunar phase, Wikipedia's article Lunar phase.
  2. Any one point or portion in a recurring series of changes, as in the changes of motion of one of the particles constituting a wave or vibration; one portion of a series of such changes, in distinction from a contrasted portion, as the portion on one side of a position of equilibrium, in contrast with that on the opposite side.
verb (phas, ing)
  1. (to phase out) To discontinue (doing) something over a period of time (i.e., in phases).
  2. (transitive) To stun or shock someone.
  3. (intransitive) To become stunned or shocked.
phase velocity Tweet Definition of phase velocity Like Definition of phase velocity on Facebook
  1. (physics) the velocity of propagation of a pure sine wave of infinite extent and infinitesimal amplitude
phon Tweet Definition of phon Like Definition of phon on Facebook
  1. A unit of apparent loudness, equal in number to the intensity in decibels of a 1,000-hertz tone judged to be as loud as the sound being measured.
phonon Tweet Definition of phonon Like Definition of phonon on Facebook
  1. (particles) The quantum of acoustic or vibrational energy (sound), considered a discrete particle.
phonoscope Tweet Definition of phonoscope Like Definition of phonoscope on Facebook
  1. a device that shows an image representing the acoustical properties of a musical instrument etc.
phosphoresce Tweet Definition of phosphoresce Like Definition of phosphoresce on Facebook
verbto phosphoresce
  1. to exhibit phosphorescence
phosphorescent Tweet Definition of phosphorescent Like Definition of phosphorescent on Facebook
  1. A phosphorescent substance.
  1. Having the property of emitting light for a period of time after the source of excitation is taken away, e.g., in electrostatic storage tubes and cathode-ray tubes.
photoconductive Tweet Definition of photoconductive Like Definition of photoconductive on Facebook
  1. of, relating to, or characterized by photoconductivity
photodisintegration Tweet Definition of photodisintegration Like Definition of photodisintegration on Facebook
  1. (physics) Any nuclear reaction, especially a nuclear fission, initiated by absorption of high-energy electromagnetic radiation such as a gamma ray
photoelasticity Tweet Definition of photoelasticity Like Definition of photoelasticity on Facebook
  1. a technique for studying and measuring the stresses and strains in an object by means of mechanical birefringence
photoelectric effect Tweet Definition of photoelectric effect Like Definition of photoelectric effect on Facebook
  1. (physics) The emission of electrons from the surface of a material following the absorption of electromagnetic radiation
photoelectron Tweet Definition of photoelectron Like Definition of photoelectron on Facebook
  1. (physics) An electron ejected from the surface of a material by the photoelectric effect
photoemission Tweet Definition of photoemission Like Definition of photoemission on Facebook
  1. (physics) the ejection of electrons from the surface of a solid by incident electromagnetic radiation
photofission Tweet Definition of photofission Like Definition of photofission on Facebook
  1. (physics) nuclear fission as the result of the absorption of a gamma ray or other high-energy photon
photoionization Tweet Definition of photoionization Like Definition of photoionization on Facebook
  1. alternative spelling of photoionisation
photoluminescence Tweet Definition of photoluminescence Like Definition of photoluminescence on Facebook
  1. (physics) luminescence following the absorption of a photon
photon Tweet Definition of photon Like Definition of photon on Facebook
  1. (particles) The quantum of light and other electromagnetic energy, regarded as a discrete particle having zero rest mass, no electric charge, and an indefinitely long lifetime. It is a gauge boson.
photonegative Tweet Definition of photonegative Like Definition of photonegative on Facebook
  1. (biology) having a negative phototropic or phototactic response; repelled by light
photoneutron Tweet Definition of photoneutron Like Definition of photoneutron on Facebook
  1. (physics) Any neutron produced by a photonuclear reaction
photonuclear Tweet Definition of photonuclear Like Definition of photonuclear on Facebook
  1. (physics) of or relating to any nuclear reaction involving a photon
photopositive Tweet Definition of photopositive Like Definition of photopositive on Facebook
  1. (biology) having a positive phototropic or phototactic response; attracted by light
photoproton Tweet Definition of photoproton Like Definition of photoproton on Facebook
  1. (physics) Any proton produced in a photonuclear reaction
photovoltaic effect Tweet Definition of photovoltaic effect Like Definition of photovoltaic effect on Facebook
  1. (physics) the conversion of electromagnetic radiation into electric power through absorption by a semiconducting material
physical Tweet Definition of physical Like Definition of physical on Facebook
  1. Physical examination.
How long has it been since your last physical?
adjective (wikipedia, Physical)
  1. Having to do with the body.
Are you feeling any physical effects?
  1. Having to do with the material world.
It's not so much a physical place as a state of mind.
  1. Involving bodily force.
This team plays a very physical game, so watch out.
  1. Having to do with physics.
This substance has a number of interesting physical properties.
physicist Tweet Definition of physicist Like Definition of physicist on Facebook
  1. A person whose occupation specializes in the science of physics, especially at a professional level.
physics Tweet Definition of physics Like Definition of physics on Facebook
  1. The branch of science concerned with the study of properties and interactions of space, time, matter and energy.
piezometer Tweet Definition of piezometer Like Definition of piezometer on Facebook
  1. An instrument used to measure high pressures
pile Tweet Definition of pile Like Definition of pile on Facebook
  1. A hair; hence, the fiber of wool, cotton, and the like; also, the nap when thick or heavy, as of carpeting and velvet.
Velvet soft, or plush with shaggy pile. &mdash;Cowper
  1. A covering of hair or fur.
  2. A large stake, or piece of timber, steel section pointed and driven into the earth or drilled and cast reinforced concrete, as at the bottom of a river, or in a harbor where the ground is soft, for the support of a building, a pier, or other superstructure, or to form a cofferdam, etc.
  3. The head of an arrow or spear.
  4. (heraldry) One of the ordinaries or subordinaries having the form of a wedge, usually placed palewise, with the broadest end uppermost.
  5. A mass of things heaped together; a heap; as, a pile of stones; a pile of wood.
  6. A mass formed in layers; as, a pile of shot.
  7. A funeral pile; a pyre.
  8. A large building, or mass of buildings.
  9. A bundle of pieces of wrought iron to be worked over into bars or other shapes by rolling or hammering at a welding heat; a fagot.
  10. A vertical series of alternate disks of two dissimilar metals, as copper and zinc, laid up with disks of cloth or paper moistened with acid water between them, for producing a current of electricity; &mdash; commonly called Volta"s pile, voltaic pile, or galvanic pile.
  11. The reverse (or tails) of a coin. (Obs)
  12. A hemorrhoid (usually it is in plural)
pinch effect Tweet Definition of pinch effect Like Definition of pinch effect on Facebook
  1. (physics) the magnetic self-attraction of parallel electric currents having the same direction; the restriction of a flowing plasma because of this attraction
pion Tweet Definition of pion Like Definition of pion on Facebook
  1. (particles) Any of three semistable mesons, having positive, negative or neutral charge, now known to be composed of a quark and an antiquark. <!-- either ¤€0, a neutral form with a mass 264 times that of an electron, or ¤€+ or ¤€&mdash;, a charged form with a mass 273 times that of an electron.
Note: ¤€+ is a combination of an up quark and a down antiquark, ¤€&mdash; is a combination of an up antiquark and a down quark, ¤€0 is a quantum mixture of an up quark, up antiquark pair and a down quark, down antiquark pair !-->
Planck's constant Tweet Definition of Planck Like Definition of Planck
  1. (physics) the constant of proportionality relating the energy and frequency of a photon (6.626 x 10-34 joule-seconds); also related to the indeterminacy limit in the Heisenberg uncertainty principle
plasma Tweet Definition of plasma Like Definition of plasma on Facebook
  1. (physics) A state of matter consisting of fully ionized gas
    1. A clear component of blood or lymph containing fibrin
    2. blood plasma, Blood plasma, free of suspended cells, used in transfusions
plastic flow Tweet Definition of plastic flow Like Definition of plastic flow on Facebook
  1. (physics) any fluid flow in which movement is proportional to the applied force (above the yield value)
  2. (geology) any deformation caused by a sustained force
plenum Tweet Definition of plenum Like Definition of plenum on Facebook
noun (pl2=plena)
  1. A space that is completely filled with matter
  • 1974: He lay on the long stone slant down to the slapping waves, his denim shorts, sneakers, and socks under his head for a pillow, feeling the splendour of distance in all directions, the liquid silence, the of aloneness. " Guy Davenport Tatlin!
    1. A legislative meeting (especially of the Communist Party) in which all members are present
    2. An enclosed space having greater than atmospheric pressure
    3. The space above a false ceiling used for cables, ducts etc
    4. (computing) A type of network cabling which satisfies plenum-ratings issued by the National Electrical Code. These cables are safer in case of a fire, producing less smoke and fumes.
pneumatic Tweet Definition of pneumatic Like Definition of pneumatic on Facebook
  1. (gnosticism) In gnostic theologian Valentinus' triadic grouping of man the highest type; a person focused on spiritual reality (the other two being hylic and psychic).
  1. Of, or related to air or other gases
  2. Of, or related to pneumatics
  3. Powered by, or filled with compressed air
  4. (zoology) Having cavities filled with air
  5. Spiritual; Of, or related to the pneuma
  6. (context, of a woman) well-rounded; full-breasted; bouncy (especially during sex)
"Every one says I'm awfully pneumatic," said Lenina reflectively, patting her own legs. - Aldous Huxley - Brave New World (chapter 6)
pneumatics Tweet Definition of pneumatics Like Definition of pneumatics on Facebook
  1. The branch of mechanics that deals with the mechanical properties of gases
poise Tweet Definition of poise Like Definition of poise on Facebook
noun (uncountable)
  1. A state of balance, equilibrium or stability
  2. Composure; freedom from embarrassment or affectation
  3. mien; bearing or deportment of the head or body
  4. A condition of hovering, or being suspended
  5. (physics) A cgs unit of dynamic viscosity equal to one dyne-second per square centimeter.
verbto poise (poises, poised, poising)
  1. To balance or to hover
  2. To draw up into readiness
Poisson's ratio Tweet Definition of Poisson Like Definition of Poisson
  1. Of a material in tension or compression, the ratio of the strain in the direction of the applied load to the strain normal to the load. Abbreviated ╬Ż.
porous Tweet Definition of porous Like Definition of porous on Facebook
  1. Full of tiny pores that allow fluids or gasses to pass through.
Sponges are so they can filter water while trapping food.
Concrete is , so water will slowly filter through it.
  1. (Of legislation): full of loopholes
positron Tweet Definition of positron Like Definition of positron on Facebook
  1. (particles) The antimatter equivalent of an electron, having the same mass but a positive charge
potential energy Tweet Definition of potential energy Like Definition of potential energy on Facebook
  1. the energy possessed by an object because of its position (in a gravitational or electric field), or its condition (as a stretched or compressed spring, as a chemical reactant, or by having rest mass)
pound-force Tweet Definition of pound-force Like Definition of pound-force on Facebook
  1. A unit of force equal to a mass of one avoirdupois pound times a standard acceleration of gravity, equal to about 4.44822 newtons. Symbol lbf or lbf.
PPS Tweet Definition of PPS Like Definition of PPS on Facebook
  1. Post Postscript
  2. Polyphenylene Sulfide
pressure Tweet Definition of pressure Like Definition of pressure on Facebook
noun (countable and uncountable; plural:pressures)
  1. (physics) The amount of force that is applied over a given area divided by the size of this area.
  • SI: pascal (Pa) (1 pascal equals 1 newton per square metre)
Others: bar (1 bar equals 100000 pascals), barye (Ba) (1 barye equals 0.1 pascal), pounds per square inch (psi, lbf/in2, lb/in2), torr, mmHg, atmosphere (atm)
  1. mental strain caused by one's own or others' expectations on one's own performance
She has been under lately because her boss expects her to get the job done two weeks early.
Synonyms - under the pump, under the gun
pressurize Tweet Definition of pressurize Like Definition of pressurize on Facebook
verb (pressuriz, es)
  1. To put pressure on; to put under pressure.
proton Tweet Definition of proton Like Definition of proton on Facebook
  1. (particles) A positively charged subatomic particle forming part of the nucleus of an atom and determining the atomic number of an element; the nucleus of the most common isotope of hydrogen; composed of two up quarks and a down antiquark
PSI Tweet Definition of PSI Like Definition of PSI on Facebook
  1. Pounds per square inch.
  2. Pre-Sentence Investigation.
  3. Protein Structure Initiative.
  4. Pollutant Safety Index or Pollutant Standard Index (Measuement of the air pollutant such as haze)
PSIG Tweet Definition of PSIG Like Definition of PSIG on Facebook
  1. pounds, Pounds per square inch, gauge (unit of pressure)
pulse Tweet Definition of pulse Like Definition of pulse on Facebook
  1. Any annual legume yielding from 1 to 12 grains or seeds of variable size, shape and colour within a pod, and used as food for humans or animals.
  2. (physiology) A normally regular beat felt when arteries are depressed, caused by the pumping action of the heart.
  3. A beat, throb.
  4. (music) A periodically recurring short stimulus, perceived as points in time. (DeLone? et. al. (Eds.), 1975, chap. 3) Often the stimuli are defined as identical (Cooper & Meyer, 1960). (rfc, music definition needs rewritten because the current one is copyrighted)
pyromagnetic Tweet Definition of pyromagnetic Like Definition of pyromagnetic on Facebook
  1. (obsolete) that functions as a result of heat and magnetism

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