[ ef ]

verb (used with or without object), interjection
  1. fuck: Stop effing around and get to work!Eff you, you lout!

  1. the word “fuck”; the f-word: peppering his speech with superfluous and highly offensive effs.

Verb Phrases
  1. eff off, Go away!: Eff off and die, you piece of Martian scum!

Origin of eff

1940–45; euphemism for fuck, with eff as spelled form of the name of the initial letter

Other definitions for eff. (2 of 2)


  1. efficient, efficiency.

  2. effective, effectiveness.

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use eff in a sentence

  • Wal, I toled har, Id stan' by har eff evrithing went ter h—l—an I wil, by ——.

    Among the Pines | James R. Gilmore
  • She had a little maid who attended her,—eff she called her,—and the girl stood by to watch while Anne did my bidding.

  • So I got the tackle of eff's father—rude enough it was in all conscience—and in the early afternoon I set out to the sport.

  • Then she stopped exhausted, smiled on eff, who sat like a cinder-witch all the while, and smoothed the hair from her brow.

British Dictionary definitions for eff


/ (ɛf) /

  1. euphemism for fuck taboo eff off

  2. eff and blind slang to use obscene language

Derived forms of eff

  • effing, noun, adjective, adverb

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012