The Collaborative International Dictionary of English v.0.48:

Dilute \Di*lute"\, v. t. [imp. & p. p. Diluted; p. pr. & vb.
   n. Diluting.] [L. dilutus, p. p. of diluere to wash away,
   dilute; di- = dis- + luere, equiv. to lavare to wash, lave.
   See Lave, and cf. Deluge.]
   1. To make thinner or more liquid by admixture with
      something; to thin and dissolve by mixing.
      [1913 Webster]

            Mix their watery store.
            With the chyle's current, and dilute it more.
                                                  --Blackmore.
      [1913 Webster]

   2. To diminish the strength, flavor, color, etc., of, by
      mixing; to reduce, especially by the addition of water; to
      temper; to attenuate; to weaken.
      [1913 Webster]

            Lest these colors should be diluted and weakened by
            the mixture of any adventitious light. --Sir I.
                                                  Newton.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Dilute \Di*lute"\, v. i.
   To become attenuated, thin, or weak; as, it dilutes easily.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Dilute \Di*lute"\, a. [L. dilutus, p. p.]
   Diluted; thin; weak.
   [1913 Webster]

         A dilute and waterish exposition.        --Hopkins.
   [1913 Webster]

WordNet (r) 3.0 (2006):

dilute
    adj 1: reduced in strength or concentration or quality or
           purity; "diluted alcohol"; "a dilute solution"; "dilute
           acetic acid" [syn: diluted, dilute] [ant:
           undiluted]
    v 1: lessen the strength or flavor of a solution or mixture;
         "cut bourbon" [syn: dilute, thin, thin out, reduce,
         cut]
    2: corrupt, debase, or make impure by adding a foreign or
       inferior substance; often by replacing valuable ingredients
       with inferior ones; "adulterate liquor" [syn: load,
       adulterate, stretch, dilute, debase]

Moby Thesaurus II by Grady Ward, 1.0:

71 Moby Thesaurus words for "dilute":
   abate, adulterate, adulterated, alleviate, alter, attenuate,
   baptize, bastardize, bate, blow off, cast forth, clear away,
   contaminate, corrupt, cut, debase, decrease, denaturalize,
   denature, diluted, diminish, dispel, dissipate, dissolve, doctor,
   doctor up, drive away, ease, emacerate, emaciate, etherealize,
   evaporate, expand, extenuate, fortify, impaired, impoverished,
   irrigate, lace, lessen, liquefy, mitigate, moderate, modify,
   pollute, qualify, rarefy, reduce, reduced, remit, slacken,
   sophisticated, spike, subtilize, tamper with, temper, thicken,
   thin, thin away, thin down, thin out, volatilize, washy, water,
   water down, watered-down, waterish, watery, weak, weaken,
   weakened