Datum

 Datum

noun

plural noun: data

 

1.

a piece of information.

"the fact is a datum worth taking into account"

an assumption or premise from which inferences may be drawn.

"this is not a permanent and unchangeable datum"

2.

a fixed starting point of a scale or operation.

"an accurate datum is formed by which other machining operations can be carried out"

 

An example of a datum is the assumed altitude of a specific piece of land used as the basis in calculating the altitude of the top of a mountain on the land. ... The singular form of data; for example, one datum. It is rarely used, and data, its plural form, is commonly used for both singular and plural.