Source : Webster's Revised Unabridged Dictionary (1913)

Comedo \Com"e*do\, n.; pl. {Comedones}. [L., a glutton. See
   {Comestible}.] (Med.)
   A small nodule or cystic tumor, common on the nose, etc.,
   which on pressure allows the escape of a yellow wormlike mass
   of retained oily secretion, with a black head (dirt).

Source : WordNet®

comedones
     See {comedo}

comedo
     n : a black-tipped plug clogging a pore of the skin [syn: {blackhead}]
     [also: {comedones} (pl)]