Source : Webster's Revised Unabridged Dictionary (1913)

Herbaceous \Her*ba"ceous\, a. [L. herbaceus grassy. See {Herb}.]
   Of or pertaining to herbs; having the nature, texture, or
   characteristics, of an herb; as, herbaceous plants; an
   herbaceous stem.

Source : WordNet®

herbaceous
     adj : characteristic of a nonwoody herb or plant part