Coined 1788 from Greek 'eu-' (well) + 'kalyptos' (covered) — named for the cap that covers the flower bud.
A fast-growing evergreen tree native to Australia, cultivated for timber and aromatic oil.
Modern Latin coinage by French botanist Charles Louis L'Héritier de Brutelle in 1788, from Greek eu- (well, good, true) + kalyptos (covered, hidden), from kalyptein (to cover, to conceal), from PIE *kel- (to cover, conceal, save). The PIE root *kel- also yields Latin celare (to hide), English hell (originally the concealed underworld), and helmet. The eucalyptus was named for the tight cap
The same Greek root 'kalyptein' (to cover, to hide) gives us 'Calypso' (the nymph who concealed Odysseus) and 'apocalypse' (an uncovering, a revelation).