[ dahy-uh l, dee- ]
/ ˈdaɪ əl, ˈdi- /

adjective Biology.

of or relating to a 24-hour period, especially a regular daily cycle, as of the physiology or behavior of an organism.

Origin of diel

1930–35; apparently < Latin di(ēs) day + -al1, spelling with e to avoid identity with dial
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

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