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ptosis definition

pto·sis (tō′sis)

noun

a prolapse, or falling of some organ or part; esp., the drooping of the upper eyelid, caused by the paralysis of its muscle

Etymology: ModL < Gr ptōsis, a fall, falling < piptein: see feather

Related Forms:

  • ptotic pto′·tic (-tik) adjective

Webster's New World College Dictionary Copyright © 2009 by Wiley Publishing, Inc., Cleveland, Ohio.
Used by arrangement with John Wiley & Sons, Inc.

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