Appropriation bill

What does Appropriation bill mean in American Law?

The definition of Appropriation bill in the law of the United States, as defined by the lexicographer Arthur Leff in his legal dictionary is:

A proposed statute directing the raising and expenditure of public money. Article I, § 7 of the Constitution stipulates that “all Bills for raising Revenue” must originate in the House of Representatives. Sometimes the distinction is made between appropriation bill and “revenue bill,” the latter considered to refer more precisely to one levying taxes in the strict sense, not to one doing something that will incidentally raise revenue, e.g., ordering the sale of some public lands.