Wiktionary
line-item veto
n. the power of an executive in government to nullify or cancel specific provisions of a bill, usually budget appropriations, without vetoing the entire legislative package.
Wikipedia
Line-item veto
The line-item veto, or partial veto, is a special form of veto that authorizes a chief executive to reject particular provisions of a bill enacted by a legislature without vetoing the entire bill. Many countries have different standards for invoking the line-item veto, if it exists at all. Each country or state has its own particular requirement for overriding a line-item veto.