From Charlie Chaplin biography book by Peter Ackroyd (page 3),
He confided on occasions to his friends that he was not sure of the identity of his biological father; nevertheless he took the name of a successful music-hall artist, Charles Chaplin, who was for a while married to his mother. He once said to an assistant, Eddie Sutherland, that "I don't know, actually, who my father was. He may have been, in the phrase of the period, a love child"
What does "in the phrase of the period" mean here?
Thank you in advance