In philately, indicia are markings on a mail piece (as opposed to an adhesive stamp) showing that postage has been prepaid by the sender. Indicia is the plural of the Latin word indicium, meaning distinguishing marks, signs or identifying marks. The term imprinted stamp is used more or less interchangeably, but some indicia are not imprinted stamps (see illustration of handstamp, for example).
Forms of indicia 
Indicia can take a number of forms, including printed designs or handstamps where a stamp would normally be that indicate the pre-payment of postage. Imprinted stamps on postal stationery are indicia.
See also 
- "Miller, Rick; The language of cover collecting in Linns.com Refresher Course section".
- Room, Adrian., ed. The Cassell Dictionary of Word Histories. London: Cassell & Co., 1999, p.306.
- "Wunderly, Kathleen; Foreign words spice up stamp collecting in Linns.com Refresher Course section".
- Carlton, R. Scott. The International Encyclopaedic Dictionary of Philately. Iola WI: Krause Publications, 1997, p.117. ISBN 0-87341-448-9.
- Mackay, James. Philatelic Terms Illustrated. 4th edition. London: Stanley Gibbons, 2003, p.71. ISBN 0-85259-557-3.