The Collaborative International Dictionary of English v.0.48:

Tharms \Tharms\, n. pl. [AS. [thorn]earm a gut; akin to D. & G.
   darm, Icel. [thorn]armr, Sw. & Dan. tarm. [root]53.]
   Twisted guts. [Obs. or Prov. Eng.] --Ascham.
   [1913 Webster]