The Collaborative International Dictionary of English v.0.48:

Guava \Gua"va\, n. [Sp. guayaba the guava fruit, guayabo the
   guava tree; prob. fr. the native West Indian name.]
   A tropical tree, or its fruit, of the genus Psidium. Two
   varieties are well known, the P. pyriferum, or white
   guava, and P. pomiferum, or red guava. The fruit or
   berry is shaped like a pomegranate, but is much smaller. It
   is somewhat astringent, but makes a delicious jelly.
   [1913 Webster]