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:

Diluted \Di*lut"ed\, a.
   Reduced in strength; thin; weak. -- Di*lut"ed*ly, adv.
   [1913 Webster]

WordNet (r) 3.0 (2006):

diluted
    adj 1: reduced in strength or concentration or quality or
           purity; "diluted alcohol"; "a dilute solution"; "dilute
           acetic acid" [syn: diluted, dilute] [ant:
           undiluted]

Moby Thesaurus II by Grady Ward, 1.0:

87 Moby Thesaurus words for "diluted":
   adulterated, airy, attenuate, attenuated, boyish, cut, dead,
   delicate, diaphanous, dilute, ethereal, fade, fine, fine-drawn,
   finespun, flat, flavorless, flimsy, frail, gaseous, gauzy, girlish,
   gossamer, gracile, gruelly, inane, indifferent, insipid,
   insubstantial, jejune, lacy, light, mild, milk-and-water, misty,
   papery, pappy, pulpy, rare, rarefied, reduced, sapless, savorless,
   slender, slenderish, slight, slight-made, slim, slimmish, slinky,
   small, spiceless, stale, subtile, subtle, svelte, sylphlike,
   tasteless, tenuous, thin, thin-bodied, thin-set, thin-spun,
   thinned, thinned-out, thinnish, threadlike, uncompact,
   uncompressed, unflavored, unsavory, unsubstantial, vague, vapid,
   vaporous, washy, wasp-waisted, watered, watered-down, waterish,
   watery, weak, willowy, windy, wiredrawn, wishy-washy, wispy