Definitions
1.NounA grammatical number referring to four (or more) things.
2.NounA set of points with all the combinatorial properties of a quadric (a quadric being the set of points of PG(n, q) whose coordinates satisfy a quadratic equation).
3.NounA set of four phrases, separated by pauses when speaking or commas when writing.
4.NounA foursome.
5.AdjectiveReferring to four (or more) things; of, in or relating to the quadral grammatical number.
6.AdjectiveOf or relating to quadral polynomials.