Crossword Dictionary

adulterous 

adulterous, extramarital, extracurricular - a 
characterized by adultery; "an adulterous relationship"; "extramarital affairs"; "the extracurricular activities of a philandering husband" 

wordplays

synonyms 

extramarital, extracurricular, two-timing

in a sentence 

ad an adulterous affair that nearly destroyed his marriage

The adulterous love affair between mayor and developer scandalized the conservative North Texas suburbs.

Cap off my year abroad with a stint as the adulterous flavor-of-the-month.

merriam-webster

etymology 

"pertaining to or given to adultery; illicit," c. 1600, a classical correction (replacing earlier avoutrious "addicted to adultery," c. 1400), from obsolete verb adulter (see adulterer) + -ous. Related: Adulterously. Adulterine (1640s, from Latin adulterinus) was used in the sense "pertaining to adultery, born of adultery."

etymonline