1.) a hand-held device used by postal worker to cancel stamp or apply a postal marking 2.) the impression left by a handstamp on a cover.

Cancellation or overprint applied by hand to a cover or to a stamp.

Strictly speaking, the implement used to apply a postmark by hand, but often used loosely to signify the postmark itself. Historically, some overprints were applied by means of handstamps.

a stamp (usually made of rubber) for imprinting a mark or design by hand

stamp with a rubber-stamp, usually an indication of official approval on a document

A postmark applied by hand (or the device used)  Harrow perf. Perforation of the whole sheet in a single process

A postmark or overprint applied by hand.

the hand-held device used by postal workers to cancel stamps and apply postal markings, or the impression left by this device