fornicate
🇺🇸
/ˈfɔːrnɪkeɪt/
🇬🇧
/ˈfɔːnɪkeɪt/
to engage in sexual activity with someone you are not married to
The couple decided to fornicate despite being unmarried.
カップルは未婚にもかかわらず性交を行うことに決めた。