qua·​ter·​na·​ry | \ˈkwä-tər-ˌner-ē, ˈkwä-tə-, kwə-ˈtər-nə-rē \

Definition of quaternary 

(Entry 1 of 2)

1a : of, relating to, or consisting of four units or members

b : of, relating to, or being a number system with a base of four

2 capitalized : of, relating to, or being the geological period from the end of the Tertiary to the present time or the corresponding system of rocks — see Geologic Time Table

3 : consisting of, containing, or being an atom bonded to four other atoms


plural quaternaries

Definition of quaternary (Entry 2 of 2)

1 capitalized : the Quaternary period or system of rocks

2 : a member of a group fourth in order or rank

Examples of quaternary in a Sentence

Recent Examples on the Web: Adjective

Ingestion of quaternary-ammonium compounds in dogs can cause reduced appetite, and gastric irritation including diarrhea and vomiting. Seattle Times Staff, The Seattle Times, "Huge recall of rawhide dog chew gets a lot bigger," 19 June 2017 A class of biocides known as quaternary ammonium compounds, or quats, is one chemical treatment that temporarily diminishes biofilms and their visible effects. National Geographic, "Black Slime Is Coating World Monuments—And That May Be Good," 21 Sep. 2016 The affected batch was recalled after the pet group found that the rawhide chew manufacturers in Mexico, Columbia and Brazil were using a quaternary ammonium compound mixture in the process of manufacturing the items. Lindsey Murray, Good Housekeeping, "[UPDATED] United Pet Group Adds Eight Additional Brands to Its Dog Chew Recall," 20 June 2017

Recent Examples on the Web: Noun

Today's PT lumber is treated with safer, less toxic chemicals, such as alkaline copper quaternary (ACQ) or copper azole. Joseph Truini, Popular Mechanics, "How to Choose a Deck Material That Is Right for You," 6 June 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'quaternary.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of quaternary


1605, in the meaning defined at sense 1a


1880, in the meaning defined at sense 1

History and Etymology for quaternary


Latin quaternarius, from quaterni four each

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The first known use of quaternary was in 1605

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qua·​ter·​na·​ry | \ˈkwät-ə(r)-ˌner-ē, kwə-ˈtər-nə-rē \

Medical Definition of quaternary 

(Entry 1 of 2)

: consisting of, containing, or being an atom bonded to four other atoms


plural quaternaries

Medical Definition of quaternary (Entry 2 of 2)

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Rhyming Dictionary: Words that rhyme with quaternary

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a nest or breeding place

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