Try Our Apps


The Best Internet Slang


[sur-key-dee-uh n, -kad-ee-, sur-kuh-dee-uh n] /sɜrˈkeɪ di ən, -ˈkæd i-, ˌsɜr kəˈdi ən/
noting or pertaining to rhythmic biological cycles recurring at approximately 24-hour intervals.
Origin of circadian
1955-60; < Latin circā about + di(ēs) day + -an Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2017.
Cite This Source
Examples from the Web for circadian
Contemporary Examples
British Dictionary definitions for circadian


of or relating to biological processes that occur regularly at about 24-hour intervals, even in the absence of periodicity in the environment See also biological clock
Word Origin
C20: from Latin circa about + diēs day
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Cite This Source
Word Origin and History for circadian

coined 1959 from Latin circa "about" (see circa) + diem, accusative singular of dies "day" (see diurnal). The original use is in circadian rhythm.

Online Etymology Dictionary, © 2010 Douglas Harper
Cite This Source
circadian in Medicine

circadian cir·ca·di·an (sər-kā'dē-ən, -kād'ē-, sûr'kə-dī'ən, -dē'-)
Relating to biological variations or rhythms with a cycle of about 24 hours.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Cite This Source

Word of the Day

Difficulty index for circadian

Some English speakers likely know this word

Word Value for circadian

Scrabble Words With Friends

Nearby words for circadian