The Collaborative International Dictionary of English v.0.48:

Debase \De*base"\, v. t. [imp. & p. p. Debased; p. pr. & vb.
   n. Debasing.] [Pref. de- + base. See Base, a., and cf.
   Abase.]
   To reduce from a higher to a lower state or grade of worth,
   dignity, purity, station, etc.; to degrade; to lower; to
   deteriorate; to abase; as, to debase the character by crime;
   to debase the mind by frivolity; to debase style by vulgar
   words.
   [1913 Webster]

         The coin which was adulterated and debased. --Hale.
   [1913 Webster]

         It is a kind of taking God's name in vain to debase
         religion with such frivolous disputes.   --Hooker.
   [1913 Webster]

         And to debase the sons, exalts the sires. --Pope.

   Syn: To abase; degrade. See Abase.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Debased \De*based"\, a. (Her.)
   Turned upside down from its proper position; inverted;
   reversed.
   [1913 Webster]

WordNet (r) 3.0 (2006):

debased
    adj 1: mixed with impurities [syn: adulterate, adulterated,
           debased]
    2: lowered in value; "the dollar is low"; "a debased currency"
       [syn: debased, devalued, degraded]
    3: ruined in character or quality [syn: corrupted, debased,
       vitiated]

Moby Thesaurus II by Grady Ward, 1.0:

106 Moby Thesaurus words for "debased":
   abandoned, abject, abominable, arrant, atrocious, base, beggarly,
   cheesy, contaminated, contemptible, corrupt, corrupted, couchant,
   crouched, crummy, debauched, decadent, degenerate, degraded,
   depraved, depressed, despicable, deteriorated, dirty, disgusting,
   dissolute, downcast, downthrown, execrable, fallen, flagrant, flat,
   foul, fulsome, grave, gross, heinous, knee-high, knocked flat,
   laid low, little, low, low-built, low-down, low-hung, low-level,
   low-leveled, low-lying, low-set, low-statured, lowered, lumpen,
   mangy, mean, measly, miserable, monstrous, morally polluted, neap,
   nefarious, obnoxious, odious, paltry, perverted, petty, poky,
   polluted, poor, profligate, prone, prostrate, rank, recumbent,
   reduced, reprobate, reptilian, rotten, runty, scabby, scrubby,
   scruffy, scummy, scurvy, shabby, shoddy, short, small, squalid,
   squat, squatty, steeped in iniquity, stooped, stumpy, submerged,
   sunk, sunken, supine, tainted, unelevated, unmentionable,
   vice-corrupted, vile, vitiate, vitiated, warped, wretched