Source : Webster's Revised Unabridged Dictionary (1913)

Eucalyptus \Eu`ca*lyp"tus\, n. [NL., from GR. ? well, good + ?
   covered. The buds of Eucalyptus have a hemispherical or
   conical covering, which falls off at anthesis.] (Bot.)
   A myrtaceous genus of trees, mostly Australian. Many of them
   grow to an immense height, one or two species exceeding the
   height even of the California Sequoia.

   Note: They have rigid, entire leaves with one edge turned
         toward the zenith. Most of them secrete resinous gums,
         whence they called {gum trees}, and their timber is of
         great value. {Eucalyptus Globulus} is the blue gum; {E.
         gigantea}, the stringy bark: {E. amygdalina}, the
         peppermint tree. {E. Gunnii}, the Tasmanian cider tree,
         yields a refreshing drink from wounds made in the bark
         in the spring. Other species yield oils, tars, acids,
         dyes and tans. It is said that miasmatic valleys in
         Algeria and Portugal, and a part of the unhealthy Roman
         Campagna, have been made more salubrious by planting
         groves of these trees.

Source : WordNet®

Eucalyptus globulus
     n : tall fast-growing timber tree with leaves containing a
         medicinal oil; young leaves are bluish [syn: {blue gum},
         {fever tree}]