Source : Webster's Revised Unabridged Dictionary (1913)

Guacharo \Gua*cha"ro\, n. [Cf. Sp. gu['a]charo sickly,
   dropsical, guacharaca a sort of bird.] (Zo["o]l.)
   A nocturnal bird of South America and Trinidad ({Steatornis
   Caripensis}, or {S. steatornis}); -- called also {oilbird.}

   Note: It resembles the goatsuckers and nighthawks, but feeds
         on fruits, and nests in caverns. A pure oil, used in
         place of butter, is extracted from the young by the
         natives.