(adj) coming next after the third and just before the fifth in position or time or degree or magnitude, Syn. 4th, quaternary, Example:the quaternary period of geologic time extends from the end of the tertiary period to the present
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 ]