Source : Webster's Revised Unabridged Dictionary (1913)

Trust company \Trust company\
   Any corporation formed for the purpose of acting as trustee.
   Such companies usually do more or less of a banking business.

Source : WordNet®

trust company
     n : an organization (usually with a commercial bank) that is
         engaged as a trustee or fiduciary or agent in handling
         trust funds or estates of custodial arrangements or stock
         transfers or related services [syn: {trust corporation}]