The Collaborative International Dictionary of English v.0.48:

Ghost \Ghost\ (g[=o]st), n. [OE. gast, gost, soul, spirit, AS.
   g[=a]st breath, spirit, soul; akin to OS. g[=e]st spirit,
   soul, D. geest, G. geist, and prob. to E. gaze, ghastly.]
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   1. The spirit; the soul of man. [Obs.]
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            Then gives her grieved ghost thus to lament.
                                                  --Spenser.
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   2. The disembodied soul; the soul or spirit of a deceased
      person; a spirit appearing after death; an apparition; a
      specter.
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            The mighty ghosts of our great Harrys rose. --Shak.
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            I thought that I had died in sleep,
            And was a blessed ghost.              --Coleridge.
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   3. Any faint shadowy semblance; an unsubstantial image; a
      phantom; a glimmering; as, not a ghost of a chance; the
      ghost of an idea.
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            Each separate dying ember wrought its ghost upon the
            floor.                                --Poe.
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   4. A false image formed in a telescope by reflection from the
      surfaces of one or more lenses.
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   Ghost moth (Zool.), a large European moth (Hepialus
      humuli); so called from the white color of the male, and
      the peculiar hovering flight; -- called also great
      swift.

   Holy Ghost, the Holy Spirit; the Paraclete; the Comforter;
      (Theol.) the third person in the Trinity.

   To give up the ghost or To yield up the ghost, to die; to
      expire.
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            And he gave up the ghost full softly. --Chaucer.
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            Jacob . . . yielded up the ghost, and was gathered
            unto his people.                      --Gen. xlix.
                                                  33.
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The Collaborative International Dictionary of English v.0.48:

Ghost \Ghost\, v. i.
   To die; to expire. [Obs.] --Sir P. Sidney.
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The Collaborative International Dictionary of English v.0.48:

Ghost \Ghost\, v. t.
   To appear to or haunt in the form of an apparition. [Obs.]
   --Shak.
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WordNet (r) 3.0 (2006):

ghost
    n 1: a mental representation of some haunting experience; "he
         looked like he had seen a ghost"; "it aroused specters from
         his past" [syn: ghost, shade, spook, wraith,
         specter, spectre]
    2: a writer who gives the credit of authorship to someone else
       [syn: ghostwriter, ghost]
    3: the visible disembodied soul of a dead person
    4: a suggestion of some quality; "there was a touch of sarcasm
       in his tone"; "he detected a ghost of a smile on her face"
       [syn: touch, trace, ghost]
    v 1: move like a ghost; "The masked men ghosted across the
         moonlit yard"
    2: haunt like a ghost; pursue; "Fear of illness haunts her"
       [syn: haunt, obsess, ghost]
    3: write for someone else; "How many books have you ghostwritten
       so far?" [syn: ghost, ghostwrite]

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

ghost

    (Or "zombie") The image of a user's session on IRC
   and similar systems, left when the session has been terminated
   (properly or, often, improperly) but the server (or the
   network at large) believes the connection is still active and
   belongs to a real user.

   Compare clonebot.

   (1997-04-07)


The Devil's Dictionary (1881-1906):

GHOST, n.  The outward and visible sign of an inward fear.

            He saw a ghost.
    It occupied -- that dismal thing! --
    The path that he was following.
    Before he'd time to stop and fly,
    An earthquake trifled with the eye
            That saw a ghost.
    He fell as fall the early good;
    Unmoved that awful vision stood.
    The stars that danced before his ken
    He wildly brushed away, and then
            He saw a post.
                                                      Jared Macphester

    Accounting for the uncommon behavior of ghosts, Heine mentions
somebody's ingenious theory to the effect that they are as much
afraid of us as we of them.  Not quite, if I may judge from such
tables of comparative speed as I am able to compile from memories of
my own experience.
    There is one insuperable obstacle to a belief in ghosts.  A ghost
never comes naked:  he appears either in a winding-sheet or "in his
habit as he lived."  To believe in him, then, is to believe that not
only have the dead the power to make themselves visible after there is
nothing left of them, but that the same power inheres in textile
fabrics.  Supposing the products of the loom to have this ability,
what object would they have in exercising it?  And why does not the
apparition of a suit of clothes sometimes walk abroad without a ghost
in it?  These be riddles of significance.  They reach away down and
get a convulsive grip on the very tap-root of this flourishing faith.