'Rowel' definitions:

Definition of 'rowel'

noun

A small spiked wheel at the end of a spur

From: GCIDE

Rowel \Row"el\, v. t. [imp. & p. p. Roweledor Rowelled; p. pr. & vb. n. Roweling or Rowelling.] (Far.) To insert a rowel, or roll of hair or silk, into (as the flesh of a horse). --Mortimer. [1913 Webster]

From: GCIDE

Rowel \Row"el\, n. [OF. roele, rouele, properly, a little wheel, F. rouelle collop, slice, LL. rotella a little wheel, dim. of L. rota a wheel. See Roll, and cf. Rota.]
1. The little wheel of a spur, with sharp points. [1913 Webster]
With sounding whip, and rowels dyed in blood. --Cowper. [1913 Webster]
2. A little flat ring or wheel on horses' bits. [1913 Webster]
The iron rowels into frothy foam he bit. --Spenser. [1913 Webster]
3. (Far.) A roll of hair, silk, etc., passed through the flesh of horses, answering to a seton in human surgery. [1913 Webster]