WordNet (r) 3.0 (2006):

eff
    v 1: have sexual intercourse with; "This student sleeps with
         everyone in her dorm"; "Adam knew Eve"; "Were you ever
         intimate with this man?" [syn: sleep together, roll in
         the hay, love, make out, make love, sleep with,
         get laid, have sex, know, do it, be intimate,
         have intercourse, have it away, have it off, screw,
         fuck, jazz, eff, hump, lie with, bed, have a
         go at it, bang, get it on, bonk]

The Free On-line Dictionary of Computing (19 January 2023):

Electronic Frontier Foundation
EFF

    (EFF) A group established to address social and legal
   issues arising from the impact on society of the increasingly
   pervasive use of computers as a means of communication and
   information distribution.  EFF is a non-profit civil liberties
   public interest organisation working to protect freedom of
   expression, privacy, and access to on-line resources and
   information.

   (http://eff.org/).

   (1994-12-08)