(mathematics) A quadratic polynomial, function or equation.

(geometry) A quadrilateral whose vertices all intersect a single circle.

quod vide; which see; used to reference material mentioned in text.

(in prescriptions) as much as you wish

(dated) A person of three-fourths Caucasian descent and one fourth African descent. / (Australia, dated) A person of three-quarters Caucasian descent and one quarter Aboriginal descent.

(dated) Having three-fourths Caucasian descent and one-fourth African descent.

(Christianity) Synonym of Lent. / (Christianity) Synonym of Quadragesima Sunday: the first Sunday in Lent.

An essential or indispensable element, condition, or ingredient.

Involving four elements.

A serving of four shots of espresso. / (chess) A kind of round-robin tournament between four players, where each participant plays every other participant once.