Source : Webster's Revised Unabridged Dictionary (1913)

Counterpoise \Coun"ter*poise`\ (koun"t?r-poiz`; 277), v. t.
   [imp. & p. p. {Counterpoised} (-poizd`); p. pr. & vb. n.
   {Counterpoising}.] [OE. countrepesen, counterpeisen, F.
   contrepeser. See {Counter}, adv., and {Poise}, v. t. ]
   1. To act against with equal weight; to equal in weight; to
      balance the weight of; to counterbalance.

            Weights, counterpoising one another.  --Sir K.
                                                  Digby.

   2. To act against with equal power; to balance.

            So many freeholders of English will be able to beard
            and counterpoise the rest.            --Spenser.

Counterpoise \Coun"ter*poise`\ (koun"t?r-poiz`), n. [OE.
   countrepese, OF. contrepois, F. contrepods. See {Counter},
   adv., and {Poise}, n.]
   1. A weight sufficient to balance another, as in the opposite
      scale of a balance; an equal weight.

            Fastening that to our exact balance, we put a
            metalline counterpoise into the opposite scale.
                                                  --Boyle.

   2. An equal power or force acting in opposition; a force
      sufficient to balance another force.

            The second nobles are a counterpoise to the higher
            nobility, that they grow not too potent. --Bacon.

   3. The relation of two weights or forces which balance each
      other; equilibrium; equiponderance.

            The pendulous round eart, with balanced air, In
            counterpoise.                         --Milton.

Source : WordNet®

counterpoise
     n : an equivalent counterbalancing weight [syn: {counterweight},
          {counterbalance}, {balance}, {equalizer}, {equaliser}]
     v : constitute a counterweight or counterbalance to [syn: {counterweight},
          {counterpose}]