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.

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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

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Usage

See data.

Etymology

Origin of datum

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

Explanation

One item of information, one fact, one statistic, is on its own a datum, the singular form of the more commonly used "data." If you can't find one single datum to support your theory, it's time for another theory. Whereas several bits of information taken together are called data, one is a datum. The word comes from the Latin for "something given." Datum is also used for a starting point of measurement, often used in surveying or engineering. The single datum that your experiment provided was that you are tall, dark and handsome. Now stop looking in the mirror and do some research.

Example Sentences

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

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

The street level along West 26th Street is more than three feet above that datum.

From New York Times • Apr. 4, 2017

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

Related Words

• accomplishment
• action
• case
• circumstance
• data
• evidence
• experience
• factor
• incident
• information
• performance
• phenomenon
• statistic