Imperforate : Indicates stamps without perforations or separating holes. They usually are separated by scissors and collected in pairs.

Imperf : Where there are no perforations on one or more edges of the stamp.

Imprint : The imprint of the designer or producer of the stamp which is printed on the stamp.

Imprinted stamps : Stamps other than adhesives, printed direct on postal stationery items (postcards, envelopes etc).

Invert : The central design ('vignette') or portion of a stamp printed upside-down in relation to the frame, or vice versa.

Ivory Head : Where the Queen's head on Queen Victoria stamps show white on the back of blued stamps.