1 any tree of the genus Eucalyptus, native to Australasia, cultivated for its timber and for the oil from its leaves.
2 (in full eucalyptus oil) this oil used as an antiseptic etc.
Etymology: mod.L f. EU- + Gk kaluptos covered f. kalupto to cover, the unopened flower being protected by a cap
Useful english dictionary. 2012.