cyclothymic disorder

[sī′klə-thīmĭk]
n.
  1. A chronic mood disturbance generally lasting at least two years and characterized by mood swings including periods of hypomania and depression.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.