The Collaborative International Dictionary of English v.0.48:

Snag \Snag\, v. t. [imp. & p. p. Snagged; p. pr. & vb. n.
   Snagging.]
   1. To cut the snags or branches from, as the stem of a tree;
      to hew roughly. [Prov. Eng.] --Halliwell.
      [1913 Webster]

   2. To injure or destroy, as a steamboat or other vessel, by a
      snag, or projecting part of a sunken tree. [U. S.]
      [1913 Webster]