da·​tum ˈdā-təm How to pronounce datum (audio) ˈda- How to pronounce datum (audio)
plural data ˈdā-tə How to pronounce datum (audio) ˈda- How to pronounce datum (audio)
ˈdä- How to pronounce datum (audio)
: something given or admitted especially as a basis for reasoning or inference
an important historical datum
This enormous expense—and considerable risk—to pick up a datum or two about geriatrics?Charles Krauthammer
plural datums, mathematics : something used as a basis for calculating or measuring
measuring the distance between datum points
… make things more efficient for those of us whose work requires a time datum.Robert Steinbrunn
Is data singular or plural?: Usage Guide

Data leads a life of its own quite independent of datum, of which it was originally the plural. It occurs in two constructions: as a plural noun (like earnings), taking a plural verb and plural modifiers (such as these, many, a few) but not cardinal numbers, and serving as a referent for plural pronouns (such as they, them); and as an abstract mass noun (like information), taking a singular verb and singular modifiers (such as this, much, little), and being referred to by a singular pronoun (it). Both constructions are standard. The plural construction is more common in print, evidently because the house style of several publishers mandates it.

Example Sentences

let's begin our discussion of this matter with a datum from actual experience
Recent Examples on the Web To me this seems like an important datum indeed considering how much debate there is in our society about the consumption levels of salt. Razib Khan, Discover Magazine, 4 May 2013 This datum is at the heart of a recent Ross Douthat column, Eugenics, Past and Future. Razib Khan, Discover Magazine, 19 June 2012 Beyond this one biographical datum—his presence at the Eastern Front—nothing else of his experience appeared in his letter. Cynthia Ozick, The Atlantic, 3 Aug. 2022 The actual observance is not a calendar event, but many promote the datum when larger quantum computers can publicly break PKI systems using RSA and ECC. Denis Mandich, Forbes, 10 Dec. 2021 The only memorable datum in 300 pages of chaff was the fact that, not counting his brothers, Jim Buckley had stood up as best man for five different bridegrooms. Neal B. Freeman, National Review, 5 Oct. 2020 Coronavirus testing has reached record levels in Oregon with nearly 12,000 residents receiving results in the past week, according to state data analyzed by The Oregonian/OregonLive. oregonlive, 30 Apr. 2020 But Smith and her colleagues now have solid data to back up other aspects of these creatures’ superpowered spines at a level of detail that’s never been seen before. Katherine J. Wu, Smithsonian Magazine, 30 Apr. 2020 Blacks have suffered roughly double the fatality rate of whites during the epidemic, according to city health data. Claudia Torrens, The Christian Science Monitor, 30 Apr. 2020 See More

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

Word History


Latin, from neuter of datus

First Known Use

1646, in the meaning defined at sense 1

Time Traveler
The first known use of datum was in 1646

Dictionary Entries Near datum

Cite this Entry

“Datum.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/datum. Accessed 6 Feb. 2023.

Kids Definition


da·​tum ˈdāt-əm How to pronounce datum (audio) ˈdat- How to pronounce datum (audio)
plural data -ə How to pronounce datum (audio) or datums
: something used as a basis for reasoning or arriving at a conclusion or for calculating or measuring

More from Merriam-Webster on datum

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Words Named After People

  • name tags
  • Namesake of the leotard, Jules Léotard had what profession?
How Strong Is Your Vocabulary?

Test your vocabulary with our 10-question quiz!

Solve today's spelling word game by finding as many words as you can with using just 7 letters. Longer words score more points.

Can you make 12 words with 7 letters?