adulterous adj.

early 15c., agent noun from obsolete verb adulter "commit adultery; adulterate, make impure, pollute" (late 14c.), from Latin adulterare "to corrupt" (see adulteration). The earlier form in Middle English was avouter (c. 1300), avoutrer (late 14c.), "person (usually a man) guilty of adultery," from Old French avoutrier, from the Latin verb, or from Latin adulter "adulterer, seducer," noun use of an adjective.

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."