What is a padded part of a harness which is worn on a horse's back, being fastened in place with a girth. It serves various purposes, as to keep the breeching in place, carry guides for the reins, etc called?

saddle — A padded part of a harness which is worn on a horse's back, being fastened in place with a girth. It serves various purposes, as to keep the breeching in place, carry guides for the reins, etc. (Webster's 1913.)

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