tera-

1. a combining form used in the names of units of measure equal to one trillion of a given base unit: terahertz.
2. Computers. a combining form of like function with the value 240 (=1,099,511,627,766). Abbreviation: T

prefix

1. denoting 10 12terameter
2. Also: tebi- denoting 2 40terabyte

prefix used in forming large units of measure (e.g. terabyte), 1947, from Greek teras (genitive teratos) “marvel, monster.” pref.

1. One trillion (1012):terahertz.

1. A prefix that means:
2. One trillion (1012), as in terahertz, one trillion hertz.
3. 240 (that is, 1,099,511,627,776), which is the power of two closest to a trillion, as in terabyte.