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datum

American  
[dey-tuhm, dat-uhm, dah-tuhm] / ˈdeɪ təm, ˈdæt əm, ˈdɑ təm /

noun

plural

data, datums

  1. a single piece of information, as a fact, statistic, or code; an item of data.

  2. Philosophy.

    1. any fact assumed to be a matter of direct observation.

    2. any proposition assumed or given, from which conclusions may be drawn.

  3. Also called sense datum.  Epistemology. the object of knowledge as presented to the mind.

  4. Surveying, Civil Engineering. any level surface, line, or point used as a reference in measuring elevations.

  5. Surveying. a basis for horizontal control surveys, consisting of the longitude and latitude of a certain point, the azimuth of a certain line from this point, and two constants used in defining the terrestrial spheroid.

datum British  
/ ˈdeɪtəm, ˈdɑːtəm /

noun

  1. a single piece of information; fact

  2. a proposition taken for granted, often in order to construct some theoretical framework upon it; a given See also sense datum

"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

Usage

See data.

Etymology

Origin of datum

First recorded in 1640–50; from Latin: “a thing given,” neuter past participle of dare “to give”

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

So went the prohibition on artificial intelligence in Frank Herbert’s 1965 novel “Dune,” and what was then a datum of fictional world-building is now a real and pressing concern.

From The Wall Street Journal • Nov. 13, 2025

Her death made no sense to me, other than as a brute datum.

From New York Times • Jan. 9, 2021

Moving in tandem through a sequence of points, the team builds up a series of height marks relative to a known baseline, or datum.

From BBC • Sep. 6, 2019

Researchers rate each datum for accuracy, using a system developed by SFEI.

From Scientific American • Jun. 13, 2019

No plural form is necessary, and the old singular, datum, can be left to the Romans.

From "Woe Is I" by Patricia T. O'Conner

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.