welterweight n.

1831, "heavyweight horseman," later "boxer or wrestler of a certain weight" (1896), from earlier welter "heavyweight horseman or boxer" (1804), possibly from welt (v.) "beat severely" (c. 1400).

... but at the end of the first German mile, Nature gave way, and this excellent mare was obliged to "knock under" to the extraordinary exertions she had made, and to the welter weight she carried, upwards of 13 stone. [The Sporting Magazine, September 1831]