The Collaborative International Dictionary of English v.0.48:

Myxoedema \Myx`oe*de"ma\, n. [NL. fr. Gr. ? mucus + oedema.]
   (Med.)
   A disease producing a peculiar cretinoid appearance of the
   face, slow speech, and dullness of intellect, and due to
   failure of the functions of the thyroid gland. [Also spelled
   myxedema.]-- Myx`oe*dem"a*tous, a., Myx`oe*dem"ic, a.
   [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

myxedema \myxedema\ n. (Med.)
   A pathological condition due to severe hyperthyroidism,
   marked by dry skin and swellings around lips and nose as well
   as mental and physical deterioration. [Also spelled
   myxoedema.]
   [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

myxoedema
    n 1: hypothyroidism marked by dry skin and swellings around lips
         and nose as well as mental deterioration [syn: myxedema,
         myxoedema]