The Collaborative International Dictionary of English v.0.48:

Tuberous \Tu"ber*ous\, a. [L. tuberosus: cf. F. tub['e]reux. See
   Tuber, and cf. also Tuberose.]
   [1913 Webster]
   1. Covered with knobby or wartlike prominences; knobbed.
      [1913 Webster]

   2. (Bot.) Consisting of, or bearing, tubers; resembling a
      tuber.
      [1913 Webster] -- Tu"ber*ous*ness, n.
      [1913 Webster]