The Collaborative International Dictionary of English v.0.48:

Wen \Wen\ (w[e^]n), n. [AS. wenn; akin to D. wen, LG. wenne.]
   (Med.)
   An indolent, encysted tumor of the skin; especially, a
   sebaceous cyst.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Wyn \Wyn\, Wynn \Wynn\, n. Also Wen \Wen\ [AS. w[=e]n.]
   One of the runes (?) adopted into the Anglo-Saxon, or Old
   English, alphabet. It had the value of modern English w, and
   was replaced from about a. d. 1280 at first by uu, later by
   w.

WordNet (r) 3.0 (2006):

wen
    n 1: a common cyst of the skin; filled with fatty matter (sebum)
         that is secreted by a sebaceous gland that has been blocked
         [syn: sebaceous cyst, pilar cyst, wen,
         steatocystoma]

Moby Thesaurus II by Grady Ward, 1.0:

97 Moby Thesaurus words for "wen":
   benign tumor, birthmark, blackhead, bleb, blemish, blister, boil,
   bulla, bump, bunion, callosity, callus, cancer, carbuncle,
   carcinoma, check, cicatrix, comedo, corn, crack, crater, craze,
   cyst, defacement, defect, deformation, deformity, dilatation,
   dilation, disfiguration, disfigurement, distension, distortion,
   edema, excrescence, fault, flaw, freckle, fungosity, fungus,
   furuncle, growth, hemangioma, hickey, intumescence, keloid, kink,
   lentigo, lump, malignant growth, metastatic tumor, milium, mole,
   morbid growth, needle scar, neoplasm, nevus, nonmalignant tumor,
   outgrowth, pimple, pit, pock, pockmark, port-wine mark,
   port-wine stain, proud flesh, pustule, rift, rising, sarcoma, scab,
   scar, scratch, sebaceous cyst, split, strawberry mark, sty, swell,
   swelling, swollenness, track, tumefaction, tumescence, tumidity,
   tumor, turgescence, turgescency, turgidity, twist, verruca,
   vesicle, wale, warp, wart, weal, welt, whitehead