Source : Webster's Revised Unabridged Dictionary (1913)

Semen \Se"men\, n.; pl. {Semina}. [L., from the root of serere,
   satum, to sow. See {Sow} to scatter seed.]
   1. (Bot.) The seed of plants.

   2. (Physiol.) The seed or fecundating fluid of male animals;
      sperm. It is a white or whitish viscid fluid secreted by
      the testes, characterized by the presence of spermatozoids
      to which it owes its generative power.

   {Semen contra}, or {Semen cin[ae] or cyn[ae]}, a strong
      aromatic, bitter drug, imported from Aleppo and Barbary,
      said to consist of the leaves, peduncles, and unexpanded
      flowers of various species of {Artemisia}; wormseed.

Artemisia \Ar`te*mi"si*a\ ([aum]rt[-e]"m[i^]zh"[i^]*[.a] or
   [aum]rt[-e]"m[i^]sh"[i^]*[.a]), n. [L. Artemisia, Gr.
   'Artemisi`a.] (Bot.)
   A genus of plants including the plants called mugwort,
   southernwood, and wormwood. Of these {A. absinthium}, or
   common wormwood, is well known, and {A. tridentata} is the
   sage brush of the Rocky Mountain region.

Source : WordNet®

artemisia
     n : any of various composite shrubs or herbs of the genus
         Artemisia having aromatic green or grayish foliage