qua·​ter·​na·​ry | \ ˈkwä-tər-ˌner-ē How to pronounce quaternary (audio) , ˈkwä-tə-, kwə-ˈtər-nə-rē How to pronounce quaternary (audio) \

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 geologic 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 Transfers from other hospital systems are limited to those requiring quaternary care and must be coordinated through the system’s Mission Control. Kristen Jordan Shamus, Detroit Free Press, 6 Jan. 2022 Most regions across the U.S. have several small hospitals dealing with the bulk of the common issues that require hospitalization along with one or two tertiary or quaternary care institutions able to handle patients with more specialized needs. Suparna Dutta, STAT, 20 Sep. 2021 Two disinfectants known to be sprayed at Glades are called Mint and Maxim Neutral, and their ingredients that have raised concern are known as quaternary ammonium compounds, or QACs. Matthew Phelan, Scientific American, 17 Sep. 2021 With the additions, the north-side facility will seek to become a regional quaternary care center, which will provide specialty complex care to patients from around the state as well as the region, hospital officials said. Alexandria Burris, The Indianapolis Star, 4 June 2021 El Centro Regional is not a tertiary or quaternary care center, meaning it’s not a hospital with extensive specialty service or care. Carolyn Barber, Fortune, 1 Dec. 2020 Snee's chemical blenders then began working to develop a new combination of quaternary ammonium compounds that could be proven to kill SARS-CoV-2 and therefore be allowed by the EPA to label their product as such. Anthony Mcauley | Staff Writer, NOLA.com, 21 Aug. 2020 SurfaceWise2′s active ingredient is quaternary ammonium, which is widely used as a disinfectant in hospitals against bacteria, fungi and certain viruses. Ashton Nichols, Dallas News, 2 June 2020 The National Institutes of Health has designated quaternary ammonium as asthma-causing and irritable to eyes and skin, flammable and corrosive, harmful to aquatic ecosystems, and persistent in the environment. Ashton Nichols, Dallas News, 2 June 2020 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, 6 June 2017 See More

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.

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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Time Traveler for quaternary

Time Traveler

The first known use of quaternary was in 1605

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Dictionary Entries Near quaternary



quaternary ammonium compound

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Statistics for quaternary

Cite this Entry

“Quaternary.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/quaternary. Accessed 6 Jul. 2022.

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More Definitions for quaternary


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

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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