The Collaborative International Dictionary of English v.0.48:

Sebaceous \Se*ba"ceous\, a. [NL. sebaceus, from L. sebum tallow,
   grease.] (Physiol.)
   Pertaining to, or secreting, fat; composed of fat; having the
   appearance of fat; as, the sebaceous secretions of some
   plants, or the sebaceous humor of animals.
   [1913 Webster]

   Sebaceous cyst (Med.), a cyst formed by distention of a
      sebaceous gland, due to obstruction of its excretory duct.


   Sebaceous glands (Anat.), small subcutaneous glands,
      usually connected with hair follicles. They secrete an
      oily semifluid matter, composed in great part of fat,
      which softens and lubricates the hair and skin.
      [1913 Webster]

WordNet (r) 3.0 (2006):

sebaceous cyst
    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]