A metric prefix denoting 1,000,000,000,000 (one trillion, or 1012) units. In computing, tera- refers to 240, and one terabyte (TB) of storage is approximately equal to one trillion bytes of data (actually 1,009,511,627,776 bytes). See Metric Prefix. See also Kilo-, Mega-, Giga-, Peta-, and Exa-. Tera- is usually abbreviated T.