The Collaborative International Dictionary of English v.0.48:

Detergent \De*ter"gent\, a. [L. detergens, -entis, p. pr. of
   detergere: cf. F. d['e]tergent.]
   Cleansing; purging. -- n. A substance which cleanses the
   skin, as water or soap; a medicine to cleanse wounds, ulcers,
   etc.
   [1913 Webster]

WordNet (r) 3.0 (2006):

detergent
    adj 1: having cleansing power [syn: detergent, detersive]
    n 1: a surface-active chemical widely used in industry and
         laundering
    2: a cleansing agent that differs from soap but can also
       emulsify oils and hold dirt in suspension

Moby Thesaurus II by Grady Ward, 1.0:

40 Moby Thesaurus words for "detergent":
   abstergent, cathartic, cleaner, cleaning, cleaning agent,
   cleaning solvent, cleanser, cleansing, cleansing cream, cold cream,
   cream, dentifrice, depurant, depurative, diuretic, emetic, enema,
   expurgatory, holystone, lotion, lustral, mouthwash, nauseant,
   pumice stone, purgative, purge, purging, purificatory, purifier,
   purifying, rinse, shampoo, soap, solvent, surfactant,
   synthetic detergent, tooth powder, toothpaste, wash, washing