Source : Webster's Revised Unabridged Dictionary (1913)

Daemon \D[ae]"mon\, n., Daemonic \D[ae]*mon"ic\, a.
   See {Demon}, {Demonic}.

Source : WordNet®

daemon
     n 1: one of the evil spirits of traditional Jewish and Christian
          belief [syn: {devil}, {fiend}, {demon}, {daimon}]
     2: a person who is part mortal and part god [syn: {demigod}]

Source : Free On-Line Dictionary of Computing

daemon
     
         /day'mn/ or /dee'mn/ (From the mythological
        meaning, later rationalised as the acronym "Disk And Execution
        MONitor") A program that is not invoked explicitly, but lies
        dormant waiting for some condition(s) to occur.  The idea is
        that the perpetrator of the condition need not be aware that a
        daemon is lurking (though often a program will commit an
        action only because it knows that it will implicitly invoke a
        daemon).
     
        For example, under {ITS} writing a file on the {LPT} spooler's
        directory would invoke the spooling daemon, which would then
        print the file.  The advantage is that programs wanting files
        printed need neither compete for access to, nor understand any
        idiosyncrasies of, the {LPT}.  They simply enter their
        implicit requests and let the daemon decide what to do with
        them.  Daemons are usually spawned automatically by the
        system, and may either live forever or be regenerated at
        intervals.
     
        {Unix} systems run many daemons, chiefly to handle requests
        for services from other {host}s on a {network}.  Most of these
        are now started as required by a single real daemon, {inetd},
        rather than running continuously.  Examples are {cron} (local
        timed command execution), {rshd} (remote command execution),
        {rlogind} and {telnetd} (remote login), {ftpd}, {nfsd} (file
        transfer), {lpd} (printing).
     
        Daemon and {demon} are often used interchangeably, but seem to
        have distinct connotations (see {demon}).  The term "daemon"
        was introduced to computing by {CTSS} people (who pronounced
        it /dee'mon/) and used it to refer to what {ITS} called a
        {dragon}.
     
        [{Jargon File}]
     
        (1995-05-11)