tera- [TE ruh]
(Greek: "monster, marvel"; a decimal prefix used in the international metric system for measurements)
Used in the metric [decimal] system as one trillion [U.S.] and billionfold [U.K.]: 1012 [1 000 000 000 000] or a million million. The metric symbol for tera- is T.
According to the Academic Press Dictionary of Science and Technology, Harcourt Brace Jovanovich, Publishers, 1992: Tera- comes "from a Greek term meaning 'marvel' or 'monster,' with the sense that this is a huge and marvelous quantity." Oh, PLEASE!
It would make much more sense to have tera based on tetra- (Greek), "four" rather then terato-, "monster, marvel"; which has no relative connection with this or any other metric unit.