Source : Webster's Revised Unabridged Dictionary (1913)

Tetramerous \Te*tram"er*ous\, a. [Tetra- + Gr. ? part.]
   1. (Bot.) Having the parts arranged in sets of four; as, a
      tetramerous flower.

   2. (Zo["o]l.) Having four joints in each of the tarsi; --
      said of certain insects.

Source : WordNet®

tetramerous
     adj : having or consisting of four similar parts; tetramerous
           flowers