Source : WordNet®

thermoplastic
     adj : having the property of softening or fusing when heated and
           of hardening and becoming rigid again when cooled;
           "thermoplastic materials can be remelted and cooled
           time after time without undergoing any appreciable
           chemical change" [ant: {thermosetting}]
     n : a material that softens when heated and hardens again when
         cooled [syn: {thermoplastic resin}]