fornicate UK /ˈfɔː.nɪ.kət/US /ˈfɔɹ.nɪ.kət/adjective 1/ˈfɔɹ.nɪˌkeɪt/ verb 1forms 5 adjective1 •Shaped like an arch or vault; resembling a fornix. fornicate UK /ˈfɔː.nɪˌkeɪt/US /ˈfɔɹ.nɪˌkeɪt/ verb1 •To engage in fornication. formsfornicated · fornicating · fornicates · more fornicate · most fornicate