Source : WordNet®

terabyte
     n : a unit of information equal to a trillion
         (1,099,511,627,776) bytes or 1024 gigabytes [syn: {T}, {TB}]

Source : Free On-Line Dictionary of Computing

terabyte
     
         2^40 = 1,099,511,627,776 {bytes} = 1024 {gigabytes} or
        roughly 10^12 bytes.
     
        (Note the spelling - one 'r').  See {prefix}.
     
        (1995-09-29)