The Collaborative International Dictionary of English v.0.48:

Felt \Felt\, v. t. [imp. & p. p. Felted; p. pr. & vb. n.
   Felting.]
   1. To make into felt, or a feltike substance; to cause to
      adhere and mat together. --Sir M. Hale.
      [1913 Webster]

   2. To cover with, or as with, felt; as, to felt the cylinder
      of a steam engine.
      [1913 Webster]

WordNet (r) 3.0 (2006):

felted
    adj 1: made by combining fibers with a binder using heat and
           pressure; "felt is a felted cloth"