noun
1. : a female friend
no other relatives … no lady friend with whom you could stay — William Black
less a secretary than an intimate lady friend — H.J.Laski
2. : a man's female companion
soldiers, and bankers, and their wives and lady friends — New Yorker
spending the day at the beach with his lady friend
3. : the female partner in an intimate especially an illicit relationship : lover , mistress