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:

Holy \Ho"ly\, a. [Compar. Holier; superl. Holiest.] [OE.
   holi, hali, AS. h[=a]lig, fr. h[ae]l health, salvation,
   happiness, fr. h[=a]l whole, well; akin to OS. h?lag, D. & G.
   heilig, OHG. heilac, Dan. hellig, Sw. helig, Icel. heilagr.
   See Whole, and cf. Halibut, Halidom, Hallow,
   Hollyhock.]
   1. Set apart to the service or worship of God; hallowed;
      sacred; reserved from profane or common use; holy vessels;
      a holy priesthood. "Holy rites and solemn feasts."
      --Milton.
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   2. Spiritually whole or sound; of unimpaired innocence and
      virtue; free from sinful affections; pure in heart; godly;
      pious; irreproachable; guiltless; acceptable to God.
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            Now through her round of holy thought
            The Church our annual steps has brought. --Keble.
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   Holy Alliance (Hist.), a league ostensibly for conserving
      religion, justice, and peace in Europe, but really for
      repressing popular tendencies toward constitutional
      government, entered into by Alexander I. of Russia,
      Francis I. of Austria, and Frederic William III. of
      Prussia, at Paris, on the 26th of September, 1815, and
      subsequently joined by all the sovereigns of Europe,
      except the pope and the king of England.

   Holy bark. See Cascara sagrada.

   Holy Communion. See Eucharist.

   Holy family (Art), a picture in which the infant Christ,
      his parents, and others of his family are represented.

   Holy Father, a title of the pope.

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

   Holy Grail. See Grail.

   Holy grass (Bot.), a sweet-scented grass (Hierochloa
      borealis and Hierochloa alpina). In the north of Europe
      it was formerly strewed before church doors on saints'
      days; whence the name. It is common in the northern and
      western parts of the United States. Called also vanilla
      grass or Seneca grass.

   Holy Innocents' day, Childermas day.

   Holy Land, Palestine, the birthplace of Christianity.

   Holy office, the Inquisition.

   Holy of holies (Script.), the innermost apartment of the
      Jewish tabernacle or temple, where the ark was kept, and
      where no person entered, except the high priest once a
      year.

   Holy One.
      (a) The Supreme Being; -- so called by way of emphasis. "
          The Holy One of Israel." --Is. xliii. 14.
      (b) One separated to the service of God.

   Holy orders. See Order.

   Holy rood, the cross or crucifix, particularly one placed,
      in churches. over the entrance to the chancel.

   Holy rope, a plant, the hemp agrimony.

   Holy Saturday (Eccl.), the Saturday immediately preceding
      the festival of Easter; the vigil of Easter.

   Holy Spirit, same as Holy Ghost (above).

   Holy Spirit plant. See Dove plant.

   Holy thistle (Bot.), the blessed thistle. See under
      Thistle.

   Holy Thursday. (Eccl.)
      (a) (Episcopal Ch.) Ascension day.
      (b) (R. C. Ch.) The Thursday in Holy Week; Maundy
          Thursday.

   Holy war, a crusade; an expedition carried on by Christians
      against the Saracens in the Holy Land, in the eleventh,
      twelfth, and thirteenth centuries, for the possession of
      the holy places.

   Holy water (Gr. & R. C. Churches), water which has been
      blessed by the priest for sacred purposes.

   Holy-water stoup, the stone stoup or font placed near the
      entrance of a church, as a receptacle for holy water.

   Holy Week (Eccl.), the week before Easter, in which the
      passion of our Savior is commemorated.

   Holy writ, the sacred Scriptures. " Word of holy writ."
      --Wordsworth.
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WordNet (r) 3.0 (2006):

Holy Ghost
    n 1: the third person in the Trinity; Jesus promised the
         Apostles that he would send the Holy Spirit after his
         Crucifixion and Resurrection; it came on Pentecost [syn:
         Holy Ghost, Holy Spirit, Paraclete]

Easton's 1897 Bible Dictionary:

Holy Ghost
   the third Person of the adorable Trinity.

     His personality is proved (1) from the fact that the
   attributes of personality, as intelligence and volition, are
   ascribed to him (John 14:17, 26; 15:26; 1 Cor. 2:10, 11; 12:11).
   He reproves, helps, glorifies, intercedes (John 16:7-13; Rom.
   8:26). (2) He executes the offices peculiar only to a person.
   The very nature of these offices involves personal distinction
   (Luke 12:12; Acts 5:32; 15:28; 16:6; 28:25; 1 Cor. 2:13; Heb.
   2:4; 3:7; 2 Pet. 1:21).

     His divinity is established (1) from the fact that the names
   of God are ascribed to him (Ex. 17:7; Ps. 95:7; comp. Heb.
   3:7-11); and (2) that divine attributes are also ascribed to
   him, omnipresence (Ps. 139:7; Eph. 2:17, 18; 1 Cor. 12:13);
   omniscience (1 Cor. 2:10, 11); omnipotence (Luke 1:35; Rom.
   8:11); eternity (Heb. 9:4). (3) Creation is ascribed to him
   (Gen. 1:2; Job 26:13; Ps. 104:30), and the working of miracles
   (Matt. 12:28; 1 Cor. 12:9-11). (4) Worship is required and
   ascribed to him (Isa. 6:3; Acts 28:25; Rom. 9:1; Rev. 1:4; Matt.
   28:19).