definition of
Quaternary

[1] #1 Quaternary n. [Quaternary period, Age of Man] last 2 million years. wn

[2] #2 Quaternary s. [quaternate, quaternary] consisting of or especially arranged in sets of four; "quaternate leaves"; "a quaternary compound". wn

[3] #3 Quaternary n. [four, 4, IV, tetrad, quatern, quaternion, quaternary, quaternity, quartet, quadruplet, foursome, Little Joe] the cardinal number that is the sum of three and one. wn

[4] #4 Quaternary s. [fourth, 4th, quaternary] coming next after the third and just before the fifth in position or time or degree or magnitude; "the quaternary period of geologic time extends from the end of the tertiary period to the present". wn