Definition of nycthemeral in English:

nycthemeral

(also nychthemeral)

adjective

Physiology Biology
  • Designating or characterized by a variation that occurs in a period of twenty-four hours, especially corresponding to the contrast between day and night.

Origin

Early 20th century; earliest use found in Nature: a weekly journal of science. From nycthemer- + -al. Compare French nyctéméral, nycthéméral.

Pronunciation

nycthemeral

/nɪkˈθɛm(ə)rəl//nɪkˈθɛm(ə)r(ə)l/