1. Any of numerous tall trees of the genus Eucalyptus, native to Australia and having aromatic leaves that yield an oil used medicinally and wood valued as timber.
2. Etymology: from Modern Latin, coined in 1788 by French botanist Charles Louis L'héritier de Brutelle (1746-1800) from Greek eu-, "well" + kalyptos, "covered", with reference to the coverings on the buds.