commemorative

adj

1. (not-comparable)Serving to commemorate something.

   “a commemorative plaque”

   “The centenary of Britain's most famous train has called for a commemorative and descriptive work and in this 40-page illustrated booklet the author has tried—with some success, to pour a quart into a pint pot.”

   “The plaza in front of San Francisco's City Hall was the scene Nov. 27 of two separate ceremonies commemorative of the assassinations one year ago of Mayor George Moscone and Supervisor Harvey Milk.”

noun

1. An object made to commemorate a person, mark an event, etc.
2. A postage stamp issued to commemorate, usually a person or event; also commonly applied to thematic (topical) stamp issues.

   “beautiful Pictorials, topicals, commemoratives, airmails. Introductory selection 40% discount. Ralph Rice, 15 Longlane, West Hartford 7, Conn.”