Etymology

infradian

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Today it means: Cyclical with a periodicity significantly longer than 24 hours, that is, less frequent than circadian. Full definition →

Latin infra
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The story

  1. Latin · derived frominfra“below”
  2. English todayinfradian

Uncertain. Possibly from the Latin infra (“below”) and diēs (“a day”) with the English suffix -an. Compare circadian, ultradian, and infra etc.

Words from the same roots

Latininfra all →

infrafracas

Etymology from Wiktionary, CC BY-SA 4.0.