n. 25B6; verb the horse had been tethered to a post : TIE (UP), hitch, rope, chain; fasten, secure.
unleash.
25B6; noun a dog on a tether : ROPE, chain, cord, lead, leash; restraint; halter.
25A0; at the end of one's tether AT ONE'S WITS' END, desperate, not knowing which way to turn, unable to cope; N. Amer. at the end of one's rope.