Definitions for pocket veto
Random House Webster's College Dictionary
an automatic veto of a bill, occurring when Congress adjourns within the ten-day period allowed for presidential action on the bill and the president has retained it unsigned.
a similar action on the part of any legislative executive.
Origin of pocket veto:
indirect veto of legislation by refusing to sign it
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.