The raised curved part at the back of a horse’s saddle.
Middle English (in the sense ‘a corner’): from Anglo-Norman French cantel, variant of Old French chantel, from medieval Latin cantellus, from cantus ‘corner, side’.
Samuel stood beside his horse. He loved to ride, but even with the cantle at the back for a little support, he was glad to get out of the saddle for a bit. He used that as his excuse for standing next to the pretty girl.