The Collaborative International Dictionary of English v.0.48:

Silva \Sil"va\, n.; pl. E. Silvas, L. Silvae. [L., properly,
   a wood, forest.] [Written also sylva.] (Bot.)
   (a) The forest trees of a region or country, considered
       collectively.
   (b) A description or history of the forest trees of a
       country.
       [1913 Webster]