Semele was a daughter of Cadmus and Harmonia, and the mother of Dionysus. There are two rival origins for her name. One is as a corruption of Selene or 'Seleme', so meaning 'bright'. The other is as a non-Greek word meaning 'earth'.

The 'bright' derivation makes sense if we consider Selene's name (or even that of Selemnus), and if we regard her name as similar to the 'bright' names of water-nymphs such as Electra, Galatea, Glauce and Ianthe (to say nothing of her sister Ino, who became Leucothea and a goddess of the sea).

The 'earth' sense could derive from a Thracian word zemelo, 'earth' (compare modern Russian zemlya, with identical meaning), so that she was an earth goddess with a name something like 'Zemelo'. She was also known as Thyone. The latter does seem to be a Greek name.