The Collaborative International Dictionary of English v.0.48:

Thrum \Thrum\, v. t. [imp. & p. p. Thrummed; p. pr. & vb. n.
   Thrumming.]
   1. To furnish with thrums; to insert tufts in; to fringe.
      [1913 Webster]

            Are we born to thrum caps or pick straw? --Quarles.
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   2. (Naut.) To insert short pieces of rope-yarn or spun yarn
      in; as, to thrum a piece of canvas, or a mat, thus making
      a rough or tufted surface. --Totten.
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