In British English, it refers exclusively to an item of underclothing for girls and women, defined by the OED as “With pl. I shall be blogging regularly about issues of English usage, word histories, and writing tips. Just sign up ( above the Twitter feed, in the right-hand column,if you’re on a laptop/PC at the bottom of the blog, on other platforms) and you’ll receive an email to tell you. If you enjoy this blog, and find it useful, there’s an easy way for you to find out when I blog again. In modern Greek, επώνυμο (eponimo) is the word for “surname”. Fielding’s Tom Jones, they mean that the title of the novel is its protagonist’s name. And when people refer to the eponymous hero of such and such a novel, e.g. The same Greek word for “name” has given English also anonymous and synonym(ous).
Such words, derived from someone’s name, are technically called eponyms, a word created in the 19th century from the Greek epōnumos “given as a name, giving one’s name to someone or something”, from epi “upon” + onoma “name” (ἐπώνυμος ἐπί + ὄνομα, Aeolic ὄνυμα name).
Many units of scientific measurement, both everyday and more specialized, are named after their discoverers: the Italian physicist Count Alessandro Volta gave us volts, the Scottish engineer James Watt gave us, er, … watts, and the Belfast-born Lord Kelvin gave his name to the units in which absolute temperature is measured. Perhaps less well known is the link between the mac – in British English, at any rate – that we might also wear and its inventor, the deviser of the waterproof cloth from which macs are made, Charles Macintosh (1766–1843), the Scottish inventor who patented the cloth. We probably all know that the wellies we might wear to go on walks through muddy fields are named after the Duke of Wellington, the “Iron Duke”.