The Collaborative International Dictionary of English v.0.48:

Theft \Theft\ (th[e^]ft), n. [OE. thefte, AS.
   [thorn]i['e]f[eth]e, [thorn][=y]f[eth]e, [thorn]e['o]f[eth]e.
   See Thief.]
   1. (Law) The act of stealing; specifically, the felonious
      taking and removing of personal property, with an intent
      to deprive the rightful owner of the same; larceny.
      [1913 Webster]

   Note: To constitute theft there must be a taking without the
         owner's consent, and it must be unlawful or felonious;
         every part of the property stolen must be removed,
         however slightly, from its former position; and it must
         be, at least momentarily, in the complete possession of
         the thief. See Larceny, and the Note under Robbery.
         [1913 Webster]

   2. The thing stolen. [R.]
      [1913 Webster]

            If the theft be certainly found in his hand alive, .
            . . he shall restore double.          --Ex. xxii. 4.
      [1913 Webster]

WordNet (r) 3.0 (2006):

theft
    n 1: the act of taking something from someone unlawfully; "the
         thieving is awful at Kennedy International" [syn:
         larceny, theft, thievery, thieving, stealing]