- a combining form meaning “early,” “primeval,” used in the formation of compound words: Eocene; eohippus.
Origin of eo-
- early or primevalEocene; eohippus
Word Origin and History for eo-
word-forming element used from mid-19c. (first in Eocene) in compound words formed by earth-scientists and meaning "characterized by the earliest appearance of," from Greek eos "dawn," from PIE *aus-, cognate with Modern English east (q.v.). Piltdown Man, before exposed as a fraud, was known as Eoanthropus.