In various elliptical uses. A black postage stamp.

(a specimen of) the first one-penny postage stamp issued in the United Kingdom, on 6 May 1840; also figurative.

A postage stamp valid only in a certain district.

Philately. A postage stamp which contains a misprint or other irregularity (e.g. incorrect colour or paper), esp. one which has been inadvertently…

(a) a five-cent stamp; (b) a banknote.

Philately. A revenue stamp; postal fiscal, one authorized for use as a postage stamp.

Philately. An imperforate postage stamp (see sense A. 3).

(A stamp) printed upside down relative to the next stamp in the same row or column (see quot. 1913). Frequently attributive in tête-bêche pair…

A halfpenny stamp.

Something that is provisional, esp. a provisional stamp.

a postage stamp issued for use in a (former) British colony; usually in plural.

A postage stamp that has been cancelled prior to being used on an item of mail, often to facilitate bulk mailing.

Philately. Of a postage stamp: belonging to or forming part of the standard issue of a country. Cf. provisional, adj. 1c.

Also with capital initial. Philately. A postage stamp authorizing conveyance of mail by air.

A postage stamp on which a picture or scene is printed, usually to commemorate a particular anniversary or event.

A postage stamp perforated with the initials or other insignia of an organization, esp. to prevent misuse.