Source : Webster's Revised Unabridged Dictionary (1913)

OEdema \[OE]*de"ma\, n. [NL., from Gr. ? a swelling, tumor, fr.
   ? to swell.] (Med.)
   A swelling from effusion of watery fluid in the cellular
   tissue beneath the skin or mucous membrance; dropsy of the
   subcutaneous cellular tissue. [Written also {edema}.]

Source : WordNet®

oedema
     n : swelling from excessive accumulation of serous fluid in
         tissue [syn: {edema}, {hydrops}, {dropsy}]