Definition of "datum" [da•tum]

• A fact or proposition used to draw a conclusion or make a decision. See Usage Note at data. (noun)
• A point, line, or surface used as a reference, as in surveying, mapping, or geology. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Mr. Smith's method of proving that every circle is 3-1/8 diameters is to assume that it is so, -- "if you dislike the term datum, then, by hypothesis, let 8 circumferences be exactly equal to 25 diameters," -- and then to show that every other supposition is thereby made absurd."
• "Because, according to our assumptions, the average value of a single datum is greater than the marginal value of that datum (remember, aggregation adds value), a consumer will always be willing to sell data at a price a merchant is willing to pay."
• "Unfortunately, if the marginal value175 to the consumer of a given datum is small, then the value of not disclosing that datum will in most cases be lower than either the cost of negotiating a confidentiality clause (if that option even exists), or the cost of forgoing the entire transaction."