From Longman Dictionary of Contemporary Englishamoura‧mour /əˈmʊə $ əˈmʊr/ noun [countable] SEX/HAVE SEX WITH literary a sexual relationship, especially a secret one
Examples from the Corpus
amour• Leaving her amour with strict instructions on how to find her, she retired to bed and waited.• I wish them a night as perfect as ours, mon amour.• Just today one of the missionary school youth was about to elope with his new amour.Origin amour (1300-1400) Old French Latin amor; → AMOROUS 