Source : WordNet®

swung dash
     n : a punctuation mark used in text to indicate the omission of
         a word

Source : Free On-Line Dictionary of Computing

swung dash
     
         A {character} similar to {tilde} but appearing
        in the same vertical position as a {dash}, i.e. half way up
        rather than at the top like tilde.  {ASCII} does not include a
        swung dash so tilde is used instead.
     
        It is commonly used for "approximates" or "is approximately
        equal to".
     
        (1997-06-28)