[syn: limpid, lucid, luculent, pellucid, crystal clear, perspicuous]
The Collaborative International Dictionary of English v.0.48:
Limpid \Lim"pid\ (l[i^]m"p[i^]d), a. [L. limpidus; akin to Gr.
   la`mpein to shine: cf. F. limpide. Cf. Lamp.]
   1. Characterized by clearness or transparency; clear; as, a
      limpid stream.
      [1913 Webster]
            Springs which were clear, fresh, and limpid.
                                                  --Woodward.
   2. Clear and unambiguous; lucid; easy to understand; -- of
      speech and writing; as, limpid prose.
      [PJC]
   3. Calm, untroubled, and without worry; serene.
      [PJC]
   Syn: Clear; transparent; pellucid; lucid; pure; crystal;
        translucent; bright.
        [1913 Webster]
WordNet (r) 3.0 (2006):
limpid
    adj 1: clear and bright; "the liquid air of a spring morning";
           "eyes shining with a liquid luster"; "limpid blue eyes"
           [syn: liquid, limpid]
    2: 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 crystal"
       [syn: crystalline, crystal clear, limpid, lucid,
       pellucid, transparent]
    3: (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,
       lucid, luculent, pellucid, crystal clear,
       perspicuous]
Moby Thesaurus II by Grady Ward, 1.0:
70 Moby Thesaurus words for "limpid":
   Attic, Ciceronian, chaste, classic, clean-cut, clear,
   clear as crystal, clear as day, clear-cut, coherent, connected,
   consistent, crisp, crystal, crystal-clear, crystalline, defined,
   definite, diaphane, diaphanous, direct, distinct, easy, elegant,
   explicit, express, filmy, finished, gauzy, gossamer, gossamery,
   graceful, gracile, light-pervious, loud and clear, lucid, luminous,
   natural, neat, nonopaque, peekaboo, pellucid, perspicuous, plain,
   polished, pure, refined, restrained, revealing, round, see-through,
   sheer, simple, straightforward, tasteful, terse, thin, translucent,
   transparent, transpicuous, trim, unaffected, unambiguous,
   unclouded, unconfused, unequivocal, univocal, unlabored,
   unmistakable, well-defined