Definition of datum

< dATP

datura >

da·tum    (dtm, dtm, dätm) KEY 

NOUN:

1. pl. da·ta  (-t) KEY  A fact or proposition used to draw a conclusion or make a decision. See Usage Note at data.
2. pl. da·tums A point, line, or surface used as a reference, as in surveying, mapping, or geology.

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ETYMOLOGY:
Latin, something given, from neuter past participle of dare, to give; see d- in Indo-European roots