noun: (grammar) A grammatical number referring to four (or more) things.
noun: (mathematics) A 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).
noun: (rhetoric) A set of four phrases, separated by pauses when speaking or commas when writing.
noun: A foursome.
adjective: (grammar) Referring to four (or more) things; of, in or relating to the quadral grammatical number.
adjective: (mathematics) Of or relating to quadral polynomials.
