出典:Wiktionary
After the title character in The History of Tom Jones, written by Henry Fielding and published in 1749; now perhaps also influenced by the Welsh singer of the same name and similar reputation.
The nearest synonyms (casanova, Don Juan, etc.) typically carry a connotation of actively seducing women. By contrast, a Tom Jones attracts women passively with his personal qualities, then gives in to the temptation to bed them.