Engaged in sexual relations outside of marriage; past tense of fornicate.
From Latin 'fornicari' (to fornicate), possibly derived from 'fornix' meaning arch or vault—ancient Roman brothels were supposedly located under arches. The term entered English through Middle English and became formalized in legal and religious language.
The word 'fornicate' might come from the arches under which Roman brothels operated—if true, it's a hilariously specific etymology showing how everyday locations became code words for behavior.
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