Definition of surcingles:
(n) :
A long unpadded strap to pass over and keep in place a blanket, pack or saddle on an animal.
(n) :
A piece of tack wrapped around the belly of a horse, to use when longeing.
(v) :
(transitive) To fasten with a surcingle.
(n) :
A girdle to fasten a garment, especially a cassock.