The Collaborative International Dictionary of English v.0.48:

Lewd \Lewd\ (l[=u]d), a. [Compar. Lewder (-[~e]r); superl.
   Lewdest.] [OE. lewed, lewd, lay, ignorant, vile, AS.
   l[=ae]wed laical, belonging to the laity.]
   1. Not clerical; laic; laical; hence, unlearned; simple.
      [Obs.]
      [1913 Webster]

            For if a priest be foul, on whom we trust,
            No wonder is a lewed man to rust.     --Chaucer.
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            So these great clerks their little wisdom show
            To mock the lewd, as learn'd in this as they. --Sir.
                                                  J. Davies.
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   2. Belonging to the lower classes, or the rabble; idle and
      lawless; bad; vicious. [Archaic] --Chaucer.
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            But the Jews, which believed not, . . . took unto
            them certain lewd fellows of the baser sort, . . .
            and assaulted the house of Jason.     --Acts xvii.
                                                  5.
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            Too lewd to work, and ready for any kind of
            mischief.                             --Southey.
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   3. Given to the promiscuous indulgence of lust; dissolute;
      lustful; libidinous. --Dryden.
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   4. Suiting, or proceeding from, lustfulness; involving
      unlawful sexual desire; as, lewd thoughts, conduct, or
      language.
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   Syn: Lustful; libidinous; licentious; profligate; dissolute;
        sensual; unchaste; impure; lascivious; lecherous;
        rakish; debauched. -- Lewd"ly, adv. -- Lewd"ness, n.
        [1913 Webster]

WordNet (r) 3.0 (2006):

lewd
    adj 1: suggestive of or tending to moral looseness; "lewd
           whisperings of a dirty old man"; "an indecent gesture";
           "obscene telephone calls"; "salacious limericks" [syn:
           lewd, obscene, raunchy, salacious]
    2: driven by lust; preoccupied with or exhibiting lustful
       desires; "libidinous orgies" [syn: lascivious, lewd,
       libidinous, lustful]

Moby Thesaurus II by Grady Ward, 1.0:

80 Moby Thesaurus words for "lewd":
   Fescennine, Rabelaisian, animal, aphrodisiomaniacal, bawdy, blue,
   carnal, clitoromaniacal, coarse, concupiscent, crude, debauched,
   dirty, dissolute, erotic, eroticomaniacal, erotomaniacal, fast,
   filthy, fleshly, foul, foul-mouthed, foul-spoken, foul-tongued,
   fulsome, goatish, gross, gynecomaniacal, hircine, horny, hot,
   hysteromaniacal, improper, impure, incontinent, indecent,
   indelicate, ithyphallic, lascivious, lecherous, libertine,
   libidinous, licentious, lickerish, lubricious, lubricous, lurid,
   lustful, nasty, nymphomaniacal, obscene, offensive, pornographic,
   priapic, prurient, randy, raunchy, raw, ribald, rude, ruttish,
   salacious, satyric, satyrical, scurrile, scurrilous, sensual,
   sexual, sexy, smoking-room, smutty, suggestive, sultry, unchaste,
   unclean, unprintable, unrepeatable, unvirtuous, vile, wild