cashier's check

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A check drawn by a bank on its own funds and signed by the bank's cashier.

from the GNU version of the Collaborative International Dictionary of English.

• (Banking) A check drawn by a bank upon its own funds, signed by the cashier.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A check (draft) whose drawer is its drawee.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a check issued by the officer of a bank on the banks own account (not that of a private person)