Source : Webster's Revised Unabridged Dictionary (1913)

Trial balance \Tri"al bal`ance\ (Bookkeeping)
   The testing of a ledger to discover whether the debits and
   credits balance, by finding whether the sum of the personal
   credits increased by the difference between the debit and
   credit sums in the merchandise and other impersonal accounts
   equals the sum of personal debits. The equality would not
   show that the items were all correctly posted.

Source : WordNet®

trial balance
     n : a balance of debits and credits in double-entry bookkeeping;
         drawn up to test their equality