"given to eating, voracious," 1736, from Latin edaci-, stem of edax "voracious, gluttonous," from edere "to eat" (from PIE root *ed- "to eat") + -ous. Related: Edacity (1620s); edaciously; edaciousness.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit admi "I eat;" Avestan ad- "to eat;" Greek edo "I eat;" Latin edere "to eat;" Lithuanian ėdu "I eat," ėdžioti "to devour, bite;" Hittite edmi "I eat," adanna "food;" Armenian utem "I eat;" Old Church Slavonic jasti "to eat," Russian jest "to eat;" Old Irish ithim "I eat;" Gothic itan, Old Swedish and Old English etan, Old High German essan "to eat."
word-forming element making adjectives from nouns, meaning "having, full of, having to do with, doing, inclined to," from Old French -ous, -eux, from Latin -osus (compare -ose (1)). In chemistry, "having a lower valence than forms expressed in -ic."
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Harper, D. (n.d.). Etymology of edacious. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/edacious