Source : Webster's Revised Unabridged Dictionary (1913)

Hacker \Hack"er\, n.
   One who, or that which, hacks. Specifically: A cutting
   instrument for making notches; esp., one used for notching
   pine trees in collecting turpentine; a hack.

Source : WordNet®

hacker
     n 1: someone who plays golf poorly
     2: a programmer who breaks into computer systems in order to
        steal or change or destroy information as a form of
        cyber-terrorism [syn: {cyber-terrorist}, {cyberpunk}]
     3: a programmer for whom computing is its own reward; may enjoy
        the challenge of breaking into other computers but does no
        harm; "true hackers subscribe to a code of ethics and look
        down upon crackers"
     4: one who works hard at boring tasks [syn: {hack}, {drudge}]

Source : Free On-Line Dictionary of Computing

hacker
     
         (Originally, someone who makes furniture with
        an axe) 1. A person who enjoys exploring the details of
        programmable systems and how to stretch their capabilities, as
        opposed to most users, who prefer to learn only the minimum
        necessary.
     
        2. One who programs enthusiastically (even obsessively) or who
        enjoys programming rather than just theorizing about
        programming.
     
        3. A person capable of appreciating {hack value}.
     
        4. A person who is good at programming quickly.
     
        5. An expert at a particular program, or one who frequently
        does work using it or on it; as in "a {Unix} hacker".
        (Definitions 1 through 5 are correlated, and people who fit
        them congregate.)
     
        6. An expert or enthusiast of any kind.  One might be an
        astronomy hacker, for example.
     
        7. One who enjoys the intellectual challenge of creatively
        overcoming or circumventing limitations.
     
        8. (Deprecated) A malicious meddler who tries to discover
        sensitive information by poking around.  Hence "password
        hacker", "network hacker".  The correct term is {cracker}.
     
        The term "hacker" also tends to connote membership in the
        global community defined by the net (see {The Network} and
        {Internet address}).  It also implies that the person
        described is seen to subscribe to some version of the {hacker
        ethic}.
     
        It is better to be described as a hacker by others than to
        describe oneself that way.  Hackers consider themselves
        something of an elite (a meritocracy based on ability), though
        one to which new members are gladly welcome.  Thus while it is
        gratifying to be called a hacker, false claimants to the title
        are quickly labelled as "bogus" or a "{wannabee}".
     
        9. (University of Maryland, rare) A programmer who does not
        understand proper programming techniques and principles and
        doesn't have a Computer Science degree.  Someone who just
        bangs on the keyboard until something happens.  For example,
        "This program is nothing but {spaghetti code}.  It must have
        been written by a hacker".
     
        [{Jargon File}]
     
        (1996-08-26)