The Collaborative International Dictionary of English v.0.48:

Excrescence \Ex*cres"cence\n. [F. excrescence, excroissanse, L.
   excrescentia excrescences, neut. pl. of p. pr. of excrescere.
   See Excrescent.]
   An excrescent appendage, as, a wart or tumor; anything
   growing out unnaturally from anything else; a preternatural
   or morbid development; hence, a troublesome superfluity; an
   incumbrance; as, an excrescence on the body, or on a plant.
   "Excrescences of joy." --Jer. Taylor.
   [1913 Webster]

         The excrescences of the Spanish monarchy. --Addison.
   [1913 Webster]

WordNet (r) 3.0 (2006):

excrescence
    n 1: something that bulges out or is protuberant or projects
         from its surroundings; "the gun in his pocket made an
         obvious bulge"; "the hump of a camel"; "he stood on the
         rocky prominence"; "the occipital protuberance was well
         developed"; "the bony excrescence between its horns" [syn:
         bulge, bump, hump, swelling, gibbosity,
         gibbousness, jut, prominence, protuberance,
         protrusion, extrusion, excrescence]
    2: (pathology) an abnormal outgrowth or enlargement of some part
       of the body