Q From Mike Kennedy: Very often, while watching British TV crime series on TV, one hears the word tom used to refer to a (female) prostitute. Why should this be. A tom-cat, after all, is male. Is it rhyming slang?
A It seems not to be.
Tom, the usual short form for the given name Thomas, has since late Middle English been a generic name for a male, as in tomfool, tomboy (a girl who behaves more like a boy), peeping tom, and Tom, Dick, and Harry. The clue to how it became connected with a woman may lie in an old bit of Australian slang, tom-tart, recorded since 1882. This had no implication of vice at the time, being merely one of the many mildly dismissive male terms that have been around at various times for a girl friend or sweetheart, like donah, sheila or dinah. It looks as though it was formed from Tom’s tart, a generic name for a female companion.
Though tart is now an insulting term for a promiscuous woman, it was to start with a short form of sweetheart and was a compliment. John Camden Hotten defined it in his 1864 slang dictionary as “a term of approval applied by the London lower orders to a young woman for whom some affection is felt. The expression is not generally employed by the young men, unless the female is in ‘her best’.” Hence the subsidiary meaning today of tart as being an overdressed woman; it also accounts for the British verb to tart up, to dress or make oneself up in order to look attractive or eye-catching, or more generally to decorate or improve the look of something.
Though the only recorded examples of tom-tart are Australian, our best guess is that it was taken there by emigrants who had learned it in England. In time, tom-tart was abbreviated to just tom, both in Australia and in Britain, and went seriously downhill to become a deeply derogatory description.
Incidentally, Louis E Jackson and C R Hellyer, in A Vocabulary of Criminal Slang of 1914, said that a tommy was a prostitute; this is often cited in support of a derivation from the male name. This may have been a temporary form, based on tom or tom-tart. But it is much more likely that it has no bearing at all on the evolution of the English slang term, since the book was compiled in the US (Hellyer was a detective in Portland, Oregon).