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


consisting of four.
arranged in fours.
(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.
Metallurgy. (of an alloy) having four principal constituents.

noun, plural quat·er·nar·ies.



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Origin of quaternary

1400–50; late Middle English < Latin quaternārius consisting of four, equivalent to quatern(ī) four at a time + -ārius -ary
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Example sentences from the Web for quaternary

British Dictionary definitions for quaternary (1 of 2)

/ (kwəˈtɜːnərɪ) /


consisting of fours or by fours
fourth in a series
chem containing or being an atom bound to four other atoms or groupsa quaternary ammonium compound
maths having four variables

noun plural -naries

the number four or a set of four

Word Origin for quaternary

C15: from Latin quaternārius each containing four, from quaternī by fours, distributive of quattuor four

British Dictionary definitions for quaternary (2 of 2)

/ (kwəˈtɜːnərɪ) /


of, denoting, or formed in the most recent period of geological time, which succeeded the Tertiary period nearly two million years ago


the Quaternary the Quaternary period or rock system, divided into Pleistocene and Holocene (Recent) epochs or series
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medical definitions for quaternary

[ kwŏtər-nĕr′ē, kwə-tûrnə-rē ]


Consisting of four; in fours.
Relating to an atom bonded to four carbon atoms.


The member of a group or series that is fourth in order.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for quaternary

[ kwŏtər-nĕr′ē ]


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.


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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.