The Collaborative International Dictionary of English v.0.48:

Woodruff \Wood"ruff`\, Woodroof \Wood"roof`\, n. [AS. wudurofe.
   See Wood, n., and cf. Ruff a plaited collar.] (Bot.)
   A little European herb (Asperula odorata) having a pleasant
   taste. It is sometimes used for flavoring wine. See Illust.
   of Whorl.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Asperula odorata
    n 1: Old World fragrant stoloniferous perennial having small
         white flowers and narrow leaves used as flavoring and in
         sachets; widely cultivated as a ground cover; in some
         classifications placed in genus Asperula [syn: sweet
         woodruff, waldmeister, woodruff, fragrant bedstraw,
         Galium odoratum, Asperula odorata]