Definition of "commemorative"
noun
plural commemoratives
(philately) A postage stamp issued to commemorate, usually a person or event; also commonly applied to thematic (topical) stamp issues.
Quotations
beautiful Pictorials, topicals, commemoratives, airmails. Introductory selection 40% discount. Ralph Rice, 15 Longlane, West Hartford 7, Conn.
1956 December, “Classified Advertisements: Stamp collecting”, in Popular Mechanics, volume 106, number 6, page 57