The Collaborative International Dictionary of English v.0.48:

Blemish \Blem"ish\, v. t. [imp. & p. p. Blemished; p. pr. &
   vb. n. Blemishing.] [OE. blemissen, blemishen, OF. blemir,
   blesmir, to strike, injure, soil, F. bl[^e]mir to grow pale,
   fr. OF. bleme, blesme, pale, wan, F. bl[^e]me, prob. fr. Icel
   bl[=a]man the livid color of a wound, fr. bl[=a]r blue; akin
   to E. blue. OF. blemir properly signifies to beat one (black
   and) blue, and to render blue or dirty. See Blue.]
   1. To mark with deformity; to injure or impair, as anything
      which is well formed, or excellent; to mar, or make
      defective, either the body or mind.
      [1913 Webster]

            Sin is a soil which blemisheth the beauty of thy
            soul.                                 --Brathwait.
      [1913 Webster]

   2. To tarnish, as reputation or character; to defame.
      [1913 Webster]

            There had nothing passed between us that might
            blemish reputation.                   --Oldys.
      [1913 Webster]

WordNet (r) 3.0 (2006):

blemished
    adj 1: marred by imperfections [ant: unblemished, unmarred,
           unmutilated]
    2: having a blemish or flaw; "a flawed diamond"; "an irregular
       pair of jeans" [syn: blemished, flawed]

Moby Thesaurus II by Grady Ward, 1.0:

108 Moby Thesaurus words for "blemished":
   adulterated, bandy, bandy-legged, beautiless, bloated, blotted,
   bowlegged, cacophonic, cacophonous, checked, cicatrized,
   club-footed, cracked, crazed, damaged, defaced, defective,
   deficient, deformed, disfigured, distorted, dwarfed, dysphemistic,
   dysphemized, erroneous, fallible, faulty, flatfooted, flawed,
   found wanting, grotesque, homely, ill-made, ill-proportioned,
   ill-shaped, immature, impaired, imperfect, imprecise, impure,
   inaccurate, inadequate, incomplete, inelegant, inexact, keloidal,
   kinked, knock-kneed, lacking, makeshift, malformed, marred,
   mediocre, misbegotten, misproportioned, misshapen, mixed,
   monstrous, mutilated, not perfect, off, out of shape, partial,
   patchy, pigeon-toed, pimpled, pimply, plain, pug-nosed, rachitic,
   rickety, scabbed, scabby, scarified, scarred, short,
   short on looks, simous, sketchy, snub-nosed, split, spoiled,
   stumpy, swaybacked, talipedic, truncated, twisted, uglified, ugly,
   ugly as hell, ugly as sin, unaesthetic, unattractive, unbeautiful,
   uncomely, undeveloped, uneven, unfinished, unhandsome, unlovely,
   unperfected, unpleasing, unpretty, unsightly, unsound, unthorough,
   wanting, warped