verb verb, intr 1: . To say 'fuck' or a similar expletive; esp. in phr. to eff and blind, to swear continuously. (1943 —) . A.Wesker He started effing and blinding and threw their books on the floor (1959). 2:trans. and intr.euphemistic = fuckverb 2, 3, 4, 5, (1950 —) . K.Amis You young people eff off (1958); D.Sanderson You sure effed things up (1958). Hence effing, noun, adjective, and adverb (1944 —) . Private Eye The relatives get effing tough (1969).
[Variant of ef, name of the letter F, euphemistically representing fuckverb.]