The Collaborative International Dictionary of English v.0.48:

Bot \Bot\, n. (Zool.)
   See Bots.
   [1913 Webster] Botanic

WordNet (r) 3.0 (2006):

bot
    n 1: botfly larva; typically develops inside the body of a horse
         or sheep or human

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

BOT
       Back On Topic (slang, Usenet, IRC)


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

BOT
       Beginning Of Tape


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

BOT
       Broadcast Online TV


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

BOT
       Build, Operate and Transfer (networke)


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

BOT
       Bulk Only Transfer


The Jargon File (version 4.4.7, 29 Dec 2003):

bot
 n

    [common on IRC, MUD and among gamers; from ?robot?]

    1. An IRC or MUD user who is actually a program. On IRC, typically the
    robot provides some useful service. Examples are NickServ, which tries to
    prevent random users from adopting nicks already claimed by others, and
    MsgServ, which allows one to send asynchronous messages to be delivered
    when the recipient signs on. Also common are ?annoybots?, such as KissServ,
    which perform no useful function except to send cute messages to other
    people. Service bots are less common on MUDs; but some others, such as the
    ?Julia? bot active in 1990--91, have been remarkably impressive Turing-test
    experiments, able to pass as human for as long as ten or fifteen minutes of
    conversation.

    2. An AI-controlled player in a computer game (especially a first-person
    shooter such as Quake) which, unlike ordinary monsters, operates like a
    human-controlled player, with access to a player's weapons and abilities.
    An example can be found at http://www.telefragged.com/thefatal/.

    3. Term used, though less commonly, for a web spider. The file for
    controlling spider behavior on your site is officially the ?Robots
    Exclusion File? and its URL is ?http:///robots.txt?)

    Note that bots in all senses were ?robots? when the terms first appeared in
    the early 1990s, but the shortened form is now habitual.


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

bot

    (From "robot") Any type
   of autonomous software that operates as an agent for a
   user or a program or simulates a human activity.  On the
   Internet, the most popular bots are programs (called
   spiders or crawlers) used for searching.  They access web
   sites, retrieve documents and follow all the hypertext
   links in them; then they generate catalogs that are accessed
   by search engines.

   A chatbot converses with humans (or other bots).  A
   shopbot searches the Web to find the best price for a
   product.  Other bots (such as OpenSesame) observe a user's
   patterns in navigating a website and customises the site for
   that user.

   Knowbots collect specific information from websites.

   (1999-05-20)