eff

Etymology 1

A spelling of the letter f (also spelled ef), the initial letter of the vulgar term fuck. Compare pee.

verb

1. (euphemistic, slang) Fuck (the taboo swear word, but not in the sense "to copulate")
   Eff off!
   And he kept saying, "Effing this, effing that."

Etymology 2

Back-formation from ineffable

verb

1. To put into words; to express.
   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

Etymology 3

noun

1. Alternative form of ef; the name of the Latin-script letter F.
   ‘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