eff

verb2

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
2. •
   (slang, euphemistic) Synonym of fuck.

   • Eff off!
   • And he kept saying, "Effing this, effing that."

adjective1

1. •
   Abbreviation of effective (“taking effect on a given date etc.”)