Biology Relating to or exhibiting approximately 24-hour periodicity.(adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "circadian" in a sentence
"The term circadian rhythms refers to biological cycles that repeat about every twenty-four hours."
"So I think clearly what we call circadian rhythms, these oscillating clocks within the body, within cells in the body, clearly exist."
""Circadian rhythms are the outward manifestation of an internal timing system which is driven by several genetic elements, what we call circadian clock genes.""