Kamasutra 1.5.22

1.5.22

etair eva kāraṇair mahāmātrasaṃbaddhā rājasaṃbaddhā vā tatraikadeśacāriṇī kā cid anyā vā kāryasaṃpādinī vidhavā pañcamīti cārāyaṇaḥ/

Charayana thinks that under these circumstances there is also a fifth kind of of Nayika, viz., a woman who is kept by a minister, or who repairs to him occasionally; or a widow who accomplishes the purpose of a man with the person to whom she resorts.