The Collaborative International Dictionary of English v.0.48:

Gean \Gean\, n. [F. guigne the fruit of the gean; cf. OHG.
   w[imac]hsila, G. weichsel.] (Bot.)
   A species of cherry tree common in Europe (Prunus avium);
   also, the fruit, which is usually small and dark in color.
   [1913 Webster]

WordNet (r) 3.0 (2006):

gean
    n 1: wild or seedling sweet cherry used as stock for grafting
         [syn: gean, mazzard, mazzard cherry]