Source : Webster's Revised Unabridged Dictionary (1913)

Lucid \Lu"cid\, a. [L. lucidus, fr. lux, lucis, light. See
   {Light}, n.]
   1. Shining; bright; resplendent; as, the lucid orbs of
      heaven.

            Lucid, like a glowworm.               --Sir I.
                                                  Newton.

            A court compact of lucid marbles.     --Tennyson.

   2. Clear; transparent. `` Lucid streams.'' --Milton.

   3. Presenting a clear view; easily understood; clear.

            A lucid and interesting abstract of the debate.
                                                  --Macaulay.

   4. Bright with the radiance of intellect; not darkened or
      confused by delirium or madness; marked by the regular
      operations of reason; as, a lucid interval.

   Syn: Luminous; bright; clear; transparent; sane; reasonable.
        See {Luminous}.

Source : WordNet®

lucid
     adj 1: (of language) transparently clear; easily understandable;
            "writes in a limpid style"; "lucid directions"; "a
            luculent oration"- Robert Burton; "pellucid prose"; "a
            crystal clear explanation"; "a perspicuous argument"
            [syn: {limpid}, {luculent}, {pellucid}, {crystal clear},
             {perspicuous}]
     2: having a clear mind; "a lucid moment in his madness"
     3: capable of thinking and expressing yourself in a clear and
        consistent manner; "a lucid thinker"; "she was more
        coherent than she had been just after the accident" [syn:
        {coherent}, {logical}]
     4: transmitting light; able to be seen through with clarity;
        "the cold crystalline water of melted snow"; "crystal
        clear skies"; "could see the sand on the bottom of the
        limpid pool"; "lucid air"; "a pellucid brook";
        "transparent cristal" [syn: {crystalline}, {crystal clear},
         {limpid}, {pellucid}, {transparent}]

Source : Free On-Line Dictionary of Computing

LUCID
     
        1. Early query language, ca. 1965, System Development Corp,
        Santa Monica, CA.  [Sammet 1969, p.701].
     
        2. A family of dataflow languages descended from {ISWIM},
        {lazy} but {first-order}.
     
        Ashcroft & Wadge , 1981.
     
        They use a dynamic {demand driven} model.  Statements are
        regarded as equations defining a network of processors and
        communication lines, through which the data flows.  Every data
        object is thought of as an infinite {stream} of simple values,
        every function as a {filter}.  Lucid has no {data
        constructor}s such as {array}s or {record}s.  {Iteration} is
        simulated with 'is current' and 'fby' (concatenation of
        sequences).  Higher-order functions are implemented using pure
        dataflow and no closures or heaps.
     
        ["Lucid: The Dataflow Language" by Bill Wadge
         and Ed Ashcroft, c. 1985].  ["Lucid, the
        Dataflow Programming Language", W. Wadge, Academic Press
        1985].
     
        (1995-02-16)