a·dul·ter·y 
(ə-dŭltə-rē, -trē)
(ə-dŭltə-rē, -trē)n. pl. a·dul·ter·ies
Consensual sexual intercourse between a married person and a person other than the spouse.
[Middle English, from Old French adultere, from Latin adulterium, from adulter, adulterer; see ADULTERATE.]