The Collaborative International Dictionary of English v.0.48:

Av \Av\ n.
   1. the eleventh month of the civil year; the fifth month of
      the ecclesiastical year in the Jewish calendar (in July
      and August).

   Syn: Ab
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Av
    n 1: the eleventh month of the civil year; the fifth month of
         the ecclesiastical year in the Jewish calendar (in July and
         August) [syn: Ab, Av]

V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

AV
       Audio/Video, "A/V"


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

AV
       AudioVisual [macintosh] (Apple)


The Free On-line Dictionary of Computing (30 December 2018):

avatar
av

   1.  An image representing a user in a
   multi-user virtual reality (or VR-like, in the case of
   Palace) space.

   2. (CMU, Tektronix) root, superuser.  There are quite a
   few Unix computers on which the name of the superuser
   account is "avatar" rather than "root".  This quirk was
   originated by a CMU hacker who disliked the term
   "superuser", and was propagated through an ex-CMU hacker at
   Tektronix.

   [Jargon File]

   (1997-09-14)