Source : WordNet®

decompress
     v 1: restore to its uncompressed form; "decompress data" [syn: {uncompress}]
          [ant: {compress}]
     2: decrease the pressure of; "depressurize the cabin in the air
        plane" [syn: {depressurize}, {depressurise}] [ant: {pressurize},
         {pressurize}]
     3: become less tense, rest, or take one's ease; "He relaxed in
        the hot tub"; "Let's all relax after a hard day's work"
        [syn: {relax}, {loosen up}, {unbend}, {unwind}, {slow down}]
        [ant: {tense}]

Source : Free On-Line Dictionary of Computing

decompress
     
         To reverse the effects of data
        {compression}.
     
        (2001-01-30)