An Etymological Dictionary of Astronomy and Astrophysics

1. A single piece of information, as a fact, statistic, or code.
   

2. Any numerical or geometric quantity which serves as a reference or a base for measurement of other quantities.
   

3. Surveying: Any basis level (surface, line, or point) used as a reference in measuring elevations.

Etymology (EN): L. datum “given,” neuter p.p. of dare “to give, offer,” cf. Av. and O.Pers. dā- “to give, grant, yield,” Av. dadāiti “he gives,” Skt. dadáti “he gives,” Gk. didomi “I give,” PIE base *do- “to give.”

Etymology (PE): Dâdé “given,” p.p. of dâdan “to give,” Mid.Pers. dâdan “to give,” O.Pers./Av. dā- “to give, grant, yield,” akin to L. data, as above.
Dâdebon, from dâdé “datum,” + bon “basis, base,” → element.
Farâzbon, from farâz “above, up, upon,” → height,

• bon “basis, base,” as above.