Blanket Search Warrant

What does Blanket Search Warrant mean in American Law?

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

A search warrant authorizing either (a) search and seizure at more than one specifically described location; or (b) search at one location but seizure of everything there. The latter is like the old general warrant and is unlawful both at common law and under the Fourth Amendment.