[uhl-trey-dee-uh n]

Origin of ultradian

1960–65; ultra- + Latin di(ēs) day + -an
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

ultradian in Medicine


  1. Relating to or exhibiting periodic physiological activity that occurs more than once every 24 hours.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.