The Collaborative International Dictionary of English v.0.48:

Naseberry \Nase"ber`ry\ (n[=a]z"b[e^]r*r[y^]), n. [Sp. nispero
   medlar and naseberry tree, fr. L. mespilus. See Medlar.]
   (Bot.)
   A tropical fruit. See Sapodilla. [Written also nisberry.]
   [1913 Webster]