quadrangle 

noun
 a geometric shape with four angles and four straight sides
 a courtyard which is quadrangular


quadrangular 

adjective
 having the shape of a quadrangle
 in the shape of a quadrangle

quadrant 

noun
 One of the four sections made by dividing an area with two perpendicular lines.

(mathematics) The four regions of the Cartesian plane bounded by the xaxis and yaxis.

(geometry) One fourth of a circle or disc; a sector with an angle of 90°.

(nautical) A measuring device with a graduated arc of 90° used in locating an altitude.

quadratic 

adjective

(mathematics) of a class of polynomial of the form <math> y = a.x^2 + b.x + c </math>

quadratic equation 

noun (wikipedia, Quadratic equation)
 In mathematics, a quadratic equation is a polynomial equation of the second degree.

quadrature 

noun
 the process of making something square; squaring

(mathematics) the process of constructing a square having the same area as a given plane figure, or of computing that area

(astronomy) a situation in which three celestial bodies form a rightangled triangle

(physics) the condition in which the phase angle between two alternating quantities is 90Â°

quadrature of the circle 

noun

(mathematics) The problem, proposed by ancient Greek geometers, of using a finite rulerandcompass construction to make a square with the same area as a given circle.

quadrilateral 

nounquadritaleral
 a polygon having four sides.
adjective
 having four sides.

quantic 

noun A homogeneous polynomial in two or more variables.

quartic 

noun
(mathematics) an algebraic equation or function of the fourth degree
adjective
(mathematics) of, or relating to the fourth degree

quindecagon 

noun
 a polygon with fifteen sides

quintic 

noun
(mathematics) a quintic polynomial: ax^{5}+bx^{4}+cx^{3}+dx^{2}+ex+f
adjective
(mathematics) Of or relating to the fifth degree, such as a quintic polynomial which has the form ax^{5}+bx^{4}+cx^{3}+dx^{2}+ex+f (containing a term with the independant variable raised to the fifth power).

quotient 

noun

(context, arithmetic) The number resulting from the division of one number by another.
 The quotient of 12 divided by 4 is 3.

(context, mathematics) By analogy, the result of any process that is the inverse of multiplication as defined for any mathematical entities other than numbers.

(context, obsolete, rare) A quotum or quota.
