Meaning of imperf. in English:

imperf.

Pronunciation /ˈɪmpəːf/

adjective

(also imperf)
Philately
  • Of a postage stamp: taken from a sheet in which the individual stamps are not separated by rows of perforations, and hence not having perforated edges; (of a sheet of stamps) lacking perforations.

Origin

Mid 19th century; earliest use found in Stamp-collector's Magazine. Shortened from either imperforate or imperforated (originally as a graphic abbreviation).