haversine 
 noun  (trigonometry) The haversed sine.


Heaviside unit function 
 noun  (mathematics) The function whose value is zero if its independent variable is negative, and one otherwise

helical 
 adjective  in the shape of a helix

helices 
 noun
 (plural of, helix)

helix 
 noun (helixes, pl2=helices)
 (mathematics) A curve on the surface of a cylinder or cone such that its angle to a plane perpendicular to the axis is constant; the threedimensional curve seen in a screw or a spiral staircase.
 (architecture) A small volute under the abacus of a Corinthian capital.
 (anatomy) The incurved rim of the external ear.
proper noun Helix
 (zoology) A genus of land snail containing many species.

hemisphere 
 noun
 (geometry) A halfsphere, formed by a plane intersecting the center of a sphere.
 (geography) Half of the Earth, the Northern Hemisphere, Southern Hemisphere, Western Hemisphere or Eastern Hemisphere.
 (anatomy) Either of the two halves of the cerebrum.

hendecagon 
 noun (plural hendecagons)
 (geometry) A polygon with eleven sides and eleven angles.

heptad 
 noun
 a group of seven things

heptagon 
 noun (plural: heptagons)
 (geometry) A polygon with seven sides and seven angles.

heptagonal 
 adjective
 Having seven angles and sides.

heptahedron 
 noun (plural=heptahedra or heptahedrons)
 (mathematics) any polyhedron having seven faces

hex 
 noun (hexes)
 An evil spell or curse.
 A witch.
verb (hexes, hexing, hexed)
 To put a hex on.

hexad 
 noun
 A group of six.

hexagon 
 noun
 (geometry) A polygon with six sides and six angles.

hexagonal 
 adjective  (geometry) Having six edges, or having a crosssection in the form of a hexagon.
 Nuts in engineering are generally hexagonal.
 (crystallography) Having three equal axis which cross at 60Â° angles, and an unequal axis which crosses the others at 90Â° angle.

hexagram 
 noun
 A hollow sixpointed star formed by overlapping two equilateral triangles; the Star of David.
 Any of the 64 sets of solid and broken lines used for divination in the I Ching.
 A large silver coin minted during the Byzantine, Byzantine Empire.

hexahedron 
 noun (pl2=hexahedra)
 (geometry) A polyhedron with six faces; the regular hexahedron is more commonly called the cube and is one of the Platonic solids.

Hilbert space 
 noun
 (mathematics) A generalized Euclidean space in which mathematical functions take the place of points; crucial to the understanding of quantum mechanics and other applications.

homothetic 
 adjective
 (mathematics) of a function of two or more variables in which the ratio of the partial derivatives depends only on the ratio of the variables, not their value
 (economics) in which the ratio of goods demanded depends only on the ratio of their prices
 the relationship of a microcosm to a macrocosm

hundred 
 noun (plural hundreds)
 A hundreddollar bill.
 (historical) An administrative subdivision in southern English counties and other countries.
 (cricket) a hundred runs scored by a batsman
 He made a in the historic match.

hundredth 
 noun
 The person or thing in the hundredth position.
 One of a hundred equal parts of a whole. Called also percent.
adjective
 The ordinal form of the number hundred, one hundred.

hyperbolic function 
 noun
 (mathematics) A function that is derived from some arithmetic operations on the exponential function with base e and the inverse function, and was named after the corresponding similar trigonometric function.

hypergeometric distribution 
 noun
 (probability theory) A discrete probability distribution that describes the number of successes in a sequence of n draws from a finite population without replacement.

hypergeometric function 
 noun  (mathematics) Any function that is a solution of the hypergeometric equation; usually an expansion of an infinite series

hyperspace 
 noun
 (math) An ndimensional Euclidian space with n > 3.
 (math) A Euclidian space of unspecified dimension.
 (scifi) A notional space orthogonal to the usual dimensions of spacetime often used for fasterthanlight travel.
 We can only get to the Nimrodian Galaxy if we go through .
 (Video games): A means of teleporting one's character.
 I was totally surrounded, so I had to hit .

hypersphere 
 noun
 (geometry) The set of all points in a given hyperspace that are at a given distance from a given point.

hypersurface 
 noun  (mathematics) A dimensional surface in a space (often a Euclidean space) of dimension +1

hypocycloid 
 noun (plural hypocycloids)
 (geometry) The locus of a point on the circumference of a circle that rolls without slipping inside the circumference of another circle.

hypotenuse 
 noun
 (geometry) The side of a right triangle opposite the right angle.
