Tough·en v. i. & t. [imp. & p. p. Toughened p. pr. & vb. n. Toughening.] To grow or make tough, or tougher.
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 toughened
      adj 1: physically toughened; "the tough bottoms of his feet" [syn:
             tough] [ant: tender]
      2: made hard or flexible or resilient especially by heat
         treatment; "a sword of tempered steel"; "tempered glass"
         [syn: tempered, treated, hardened] [ant: untempered]