Source : Webster's Revised Unabridged Dictionary (1913)

Weightless \Weight"less\, a.
   Having no weight; imponderable; hence, light. --Shak.

Source : WordNet®

weightless
     adj : having little or no weight or apparent gravitational pull;
           light; "floating freely in a weightless condition"; "a
           baby bat...fluffy and weightless as a moth"; "jackets
           made of a weightless polyester fabric" [ant: {weighty}]