The Collaborative International Dictionary of English v.0.48:

Luminous \Lu"mi*nous\, a. [L. luminosus, fr. lumen light: cf. F.
   lumineux. See Luminary, Illuminate.]
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   1. Shining; emitting or reflecting light; brilliant; bright;
      as, the is a luminous body; a luminous color.
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            Fire burneth wood, making it . . . luminous.
                                                  --Bacon.
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            The mountains lift . . . their lofty and luminous
            heads.                                --Longfellow.
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   2. Illuminated; full of light; bright; as, many candles made
      the room luminous.
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            Up the staircase moved a luminous space in the
            darkness.                             --Longfellow.
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   3. Enlightened; intelligent; also, clear; intelligible; as, a
      luminous mind. " Luminous eloquence." --Macaulay. " A
      luminous statement." --Brougham.
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   Luminous paint, a paint made up with some phosphorescent
      substance, as sulphide of calcium, which after exposure to
      a strong light is luminous in the dark for a time.
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   Syn: Lucid; clear; shining; perspicuous.
        [1913 Webster] -- Lu"mi*nous*ly, adv. --
        Lu"mi*nous*ness, n.
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WordNet (r) 3.0 (2006):

luminous
    adj 1: softly bright or radiant; "a house aglow with lights";
           "glowing embers"; "lambent tongues of flame"; "the lucent
           moon"; "a sky luminous with stars" [syn: aglow(p),
           lambent, lucent, luminous]