pocket veto

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

• noun The indirect veto of a bill received by the President within ten days of the adjournment of Congress, effected by retaining the bill unsigned until Congress adjourns.
• noun A similar action exercised by a state governor or other chief executive.

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

• The retention by the President of the United States of a bill unsigned so that it does not become a law, in virtue of the following constitutional provision (Const. Art. I., sec. 7, cl. 2): “If any bill shall not be returned by the President within ten days (Sundays excepted) after it shall have been presented to him, the same shall be a law, in like manner as if he had signed it, unless the Congress by their adjournment prevent its return, in which case it shall not be a law.” Also, an analogous retention of a bill by a State governor.

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

• noun US A (de facto) veto of a bill by the US President by restricting Congressional action on the bill, as, figuratively, by carrying the bill in his pocket until the deadline for signing it has passed.

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

• noun indirect veto of legislation by refusing to sign it