Earliest known use (EKU) - The cover or piece that documents the earliest date on which a stamp or postal stationery item is known to be used.
Early Impression - A stamp printed during the beginning run of a press that usually has a very sharp image.
E F O - Errors, Freaks and Oddities.
Embossing - The process of giving relief to paper by pressing it with a die.
Encased postage stamp - A stamp inserted into a small, transparent, coin-size case originally used as legal coins during coin shortages.
Entire - An intact piece of postal stationery, in contrast to a cutout of the imprinted stamp.
Error - A major mistake in the production of a stamp or postal stationery item such as imperforates, missing or incorrect colors, and design image errors.
Essay - The artwork of a proposed design for a stamp.
Etiquette - A gummed label applied to an envelope to designate a specific mail service.
Examiner’s Mark - A mark indicating examination by censors.
Expertization - The examination of a stamp or cover by an acknowledged expert to determine if it is genuine.
Exploded - A stamp booklet that has been separated into its various components, usually for purposes of display.