from Wiktionary, Creative Commons Attribution/Share-Alike License.
superlativeform of uncouth: most uncouth.
Sorry, no etymologies found.
"I think he's the uncouthest of any person I ever saw."
Gentle Julia Booth Tarkington 1907
The other self, tremulous, inconsequent, full of irresistible tenderness for suffering and weakness even in its uncouthest garb, said incessantly, "I could do no less.
The Lowest Rung Together with The Hand on the Latch, St. Luke's Summer and The Understudy Mary Cholmondeley 1892