Source : Webster's Revised Unabridged Dictionary (1913)

Counterbrace \Coun"ter*brace`\, v. t.
   1. (Naut.) To brace in opposite directions; as, to
      counterbrace the yards, i. e., to brace the head yards one
      way and the after yards another.

   2. (Engin.) To brace in such a way that opposite strains are
      resisted; to apply counter braces to.