a. [ L. quaternarius consisting of four each, containing four, fr. quaterni four each, fr. quattuor four: cf. F. quaternaire. See Four. ] [ 1913 Webster ]

1. Consisting of four; by fours, or in sets of four. [ 1913 Webster ]

2. (Geol.) Later than, or subsequent to, the Tertiary; Post-tertiary; as, the Quaternary age, or Age of man. [ 1913 Webster ]

n. [ L. numerus quaternarius: cf. F. quaternaire. ] 1. The number four. Boyle. [ 1913 Webster ]

2. (Geol.) The Quaternary age, era, or formation. See the Chart of Geology. [ 1913 Webster ]

a. Composed of, or arranged in, sets of four; quaternary; as, quaternate leaves. [ 1913 Webster ]

n. [ L. quaternio, fr. quaterni four each. See Quaternary. ] 1. The number four. [ Poetic ] [ 1913 Webster ]

2. A set of four parts, things, or person; four things taken collectively; a group of four words, phrases, circumstances, facts, or the like. [ 1913 Webster ]

Delivered him to four quaternions of soldiers. Acts xii. 4. [ 1913 Webster ]

Ye elements, the eldest birth
Of Nature's womb, that in quaternion run. Milton. [ 1913 Webster ]

The triads and quaternions with which he loaded his sentences. Sir W. Scott. [ 1913 Webster ]

3. A word of four syllables; a quadrisyllable. [ 1913 Webster ]

4. (Math.) The quotient of two vectors, or of two directed right lines in space, considered as depending on four geometrical elements, and as expressible by an algebraic symbol of quadrinomial form. [ 1913 Webster ]

☞ The science or calculus of quaternions is a new mathematical method, in which the conception of a quaternion is unfolded and symbolically expressed, and is applied to various classes of algebraical, geometrical, and physical questions, so as to discover theorems, and to arrive at the solution of problems. Sir W. R. Hamilton. [ 1913 Webster ]

v. t. To divide into quaternions, files, or companies. Milton. [ 1913 Webster ]

n. [ LL. quaternitas, fr. L. quaterni four each: cf. F. quaternité. ] 1. The number four. [ Obs. ] Sir T. Browne. [ 1913 Webster ]

2. The union of four in one, as of four persons; -- analogous to the theological term trinity. [ 1913 Webster ]