Source : Webster's Revised Unabridged Dictionary (1913)

Cashier's check \Cash*ier's" check\ (Banking)
   A check drawn by a bank upon its own funds, signed by the
   cashier.

Source : WordNet®

cashier's check
     n : a check issued by the officer of a bank on the banks own
         account (not that of a private person); "cashier's checks
         are as good as cash" [syn: {treasurer's check}, {cashier's
         cheque}, {treasurer's cheque}]