The Collaborative International Dictionary of English v.0.48:

Cleanse \Cleanse\ (kl[e^]nz), v. t. [imp. & p. p. Cleansed
   (kl[e^]nzd); p. pr. & vb. n. Cleansing.] [AS. cl[=ae]nsian,
   fr. cl[=ae]ne clean. See Clean.]
   To render clean; to free from fith, pollution, infection,
   guilt, etc.; to clean.
   [1913 Webster]

         If we walk in the light . . . the blood of Jesus Christ
         his son cleanseth us from all sin.       --1 John i. 7.
   [1913 Webster]

         Can'st thou not minister to a mind diseased,
         And with some sweet oblivious antidote
         Cleanse the suffed bosom of that perilous stuff
         Which weighs upon the heart?             --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

cleanse
    v 1: clean one's body or parts thereof, as by washing; "clean up
         before you see your grandparents"; "clean your fingernails
         before dinner" [syn: cleanse, clean]
    2: purge of an ideology, bad thoughts, or sins; "Purgatory is
       supposed to cleanse you from your sins"