Definition of "eff"

eff¹

/ˈɛf/

verb
third-person singular simple present effs, present participle effing, simple past and past participle effed
1. (euphemistic, slang) Fuck (the taboo swear word, but not in the sense "to copulate")

eff²

/ˈɛf/

verb
third-person singular simple present effs, present participle effing, simple past and past participle effed
1. To put into words; to express.
  Quotations
  […] and perhaps also because what we know partakes in no small measure of the nature of what has so happily been called the unutterable or ineffable, so that any attempt to utter or eff it is doomed to fail, doomed, doomed to fail.
  1953, Samuel Beckett, Watt, Olympia Press
  They, no more than we, found it hard to eff the ineffable, but they, you see, needed to console themselves more.
  2001, Paul West, Master Class: Scenes from a Fiction Workshop, page 57
  It is another way of effing the ineffable, one with potentially serious practical effects.
  2018, Wesley J. Wildman, Effing the Ineffable: Existential Mumblings at the Limits of Language, page 83
  Douglas Adams (1952–2001), author of The Hitchhiker's Guide to the Galaxy, puts it memorably: “Let's think the unthinkable, let's do the undoable. Let us prepare to grapple with the ineffable itself, and see if we may not eff it after all.”
  2020, Tim Vivian, Other Voices, Other Rooms: Poems, page 100

eff³

/ˈɛf/

noun
plural effs
1. Alternative form of ef; the name of the Latin-script letter F.
  Quotations
  Why against printers all this noise? This summoning of blackguard boys? Why so sagacious in your guesses? Your effs, and tees, and arrs, and eſſes? Take my advice; to make you safe, I know a shorter way be half.
  a. 1746 (date written), Jonathan Swift, “On the Irish Club”, in Thomas Sheridan and John Nichols, editors, The Works of the Rev. Jonathan Swift, […], new edition, volume VIII, London: […] J[oseph] Johnson, […], published 1801, page 78
  ‘Eff. You. En,’ said Mr Banstead. ‘Fun! […]’
  1969, Michael Feld, The Sabbatical Year, London: Alan Ross Ltd, page 301
  A or an? When an indefinite article precedes an acronym or initialism, the choice between a and an follows from the pronunciation: / a FAQ file (“fack”; but “an FAQ file” with the alternate pronunciation “eff-ay-cue”) / an FTC commissioner (“eff-tee-cee”)
  2019, Amy Einsohn, Marilyn Schwartz, “[Abbreviations and Symbols] Abbreviations”, in The Copyeditor’s Handbook: A Guide for Book Publishing and Corporate Communications, 4th edition, University of California Press, part 2 (Editorial Style), page 242
  ‘S-S-C…sitting on a tree…eff-you-cee-kay-i-en-ji.’
  2019, Anand Ranganathan, Chitra Subramaniam, The Rat Eater, Bloomsbury India