BUCKLE (3)

Buc″kle (bŭk″k'l), v. i. 1. 1. To bend permanently; to become distorted; to bow; to curl; to kink.
Buckled with the heat of the fire like parchment. Pepys. 2. 2. To bend out of a true vertical plane, as a wall.
3. 3. To yield; to give way; to cease opposing.
The Dutch, as high as they seem, do begin to buckle. Pepys. 4. 4. To enter upon some labor or contest; to join in close fight; to struggle; to contend.
The bishop was as able and ready to buckle with the Lord Protector as he was with him. Latimer. In single combat thou shalt buckle with me. Shak. To buckle to, to bend to; to engage with zeal. To make our sturdy humor buckle thereto. Barrow. Before buckling to my winter's work. J. D. Forbes.