corm

from WordNet (r) 3.0 (2006)

corm
    n 1: solid swollen underground bulb-shaped stem or stem base and
         serving as a reproductive structure

from The Collaborative International Dictionary of English v.0.48

Corm \Corm\ (k[^o]rm), n. [See {Cormus}.]
   1. (Bot.) A solid bulb-shaped root, as of the crocus. See
      {Bulb}.
      [1913 Webster]

   2. (Biol.) Same as {Cormus}, 2.
      [1913 Webster]