from Wiktionary, Creative Commons Attribution/Share-Alike License.
superlativeform of unripe: most unripe.
Sorry, no etymologies found.
The publicity is so odious, and one does get bored by the passengers constantly wandering up and down the train, and the boys who pass and repass every ten minutes selling books, newspapers, cigars, candy, and the unripest of fruit, which they are always pressing you to buy; to say nothing of chewing, spitting Americans one has to countenance all day long.
I was one of five sergeants of the troop, the unripest among them and already accounted lucky.