Stayer n. One who upholds or supports that which props; one who, or that which, stays, stops, or restrains; also, colloquially, a horse, man, etc., that has endurance, as in a race.
... one. Full of vinegar and all-round cussedness, but without malice. Just as soon kill you as not, but in a playful sort of way, you understand, without meaning to at all. Personally, I wouldn't think of riding him. But he's a stayer. Look at them lungs. And look at them legs. Not a blemish. He's never been hurt or worked. Nobody ever succeeded in taking it out of him. Mountain horse, too, trail-broke and all that, being raised in rough country. Sure-footed as a goat, so long as he don't ... — Burning Daylight • Jack London
... "I suppose that's the way it goes. Hang it, I guess I was a little too sudden. But I'm a stayer. Maybe you'll change ... — Big Timber - A Story of the Northwest • Bertrand W. Sinclair