Douglas Harper's Etymology Dictionary
"the other," early 13c., þe toþer, from faulty separation of þet oþer "that other;" simple use of tother in place of the other is attested by 1580s. Often written t'other as though a contraction of the other.
Wiktionary
pron. (context now UK dialectal English) other.
Usage examples of "tother".
So each draws its lines, leaving Rabbit Notch to tother, which winds it up in none.
Twas the good Liberty cause, and all the mealy office-seekers were on our side till they saw the wind blowing tother way.
One part for your keep and your working clothes, another for your pocket, and tother, to put by and to buy your good things out of.
But the love she carried for Blake was hopeless, for when he had been in England one year ago he had not come to Ludgrove Hall but had gone instead to Oxfordshire and become bet tother to Lady Margaret Tawney, the beautiful daughter of the Earl of Rockley.
Holding her head high, squeezing her gardenia bouquet, she walked sedately down the aisle, refusing to glance tother side, refusing to admit that she felt queasy.
Aw hate fowk sanctimonious, whose humility is pride, Who, when they see a chap distressed, pass by on tother side!
I came across it one day when I saw one boltin' into the scrub and I followed through a badger run an' there was the rabbit's hole just this side of the wall, so I guessed it came up tother side.
When they'd dragged the poor bastard under the ship and got him out tother side he was drowned dead as a rat in a beer barrel.