Quaternary

[kwot-er-ner-ee, kwuh-tur-nuh-ree] /ˈkwɒt ərˌnɛr i, kwəˈtɜr nə ri/

adjective
1.
consisting of four.
2.
arranged in fours.
3.
(initial capital letter) Geology. noting or pertaining to the present period of earth history, forming the latter part of the Cenozoic Era, originating about 2 million years ago and including the Recent and Pleistocene Epochs.
4.
Metallurgy. (of an alloy) having four principal constituents.
noun, plural quaternaries.
5.
a group of four.
6.
the number four.
7.
(initial capital letter) Geology. the Quaternary Period or System.
/kwəˈtɜːnərɪ/
adjective
1.
consisting of fours or by fours
2.
fourth in a series
3.
(chem) containing or being an atom bound to four other atoms or groups: a quaternary ammonium compound
4.
(maths) having four variables
noun (pl) -naries
5.
the number four or a set of four
/kwəˈtɜːnərɪ/
adjective
1.
of, denoting, or formed in the most recent period of geological time, which succeeded the Tertiary period nearly two million years ago
noun
2.
the Quaternary, the Quaternary period or rock system, divided into Pleistocene and Holocene (Recent) epochs or series
adj.

early 15c., “consisting of four parts,” from Latin quaternarius “of four each, containing four,” from quaterni “four each, by fours,” from quater “four times,” related to quattuor “four” (see four). Also as a noun, “the number four” (mid-15c.), from Latin quaternarius.

In geological sense, attested from 1843 in English, proposed 1829 by French geologist Jules Pierre François Stanislas Desnoyers (1800-1887) as name for “the fourth great epoch of geological time,” but because it comprises only the age of man, and the other epochs are many hundred times longer, not all accepted it.

quaternary qua·ter·nar·y (kwŏt’ər-něr’ē, kwə-tûr’nə-rē)
adj.

n.
The member of a group or series that is fourth in order.
quaternary
(kwŏt’ər-něr’ē)
Noun Quaternary. The second and last period of the Cenozoic Era, from about 2 million years ago to the present. During this time the continents were situated approximately as they are today, although the geography was different due to fluctuations in sea levels caused by the advance and retreat of ice sheets. Humans first appeared during this period. See Chart at geologic time.

Adjective Relating to or having a carbon atom that is attached to four other carbon atoms in a molecule. Quaternary pentane, for example, contains five carbon atoms of which one is in the center and the other four are each attached to it.