Roister is related to French ruste, meaning "rude" or "rough." That word comes from the fairly neutral Latin rusticus, meaning "rural." Originally, the English verb was simply roist, and one who roisted was a roister. Those words are no longer used; instead, we have the verb roister, and the corresponding noun roisterer.
Verb the earl's wastrel son had spent the best part of his youth roistering and gambling
Recent Examples on the Web
Verb
One of his sons, Thomas (Dean-Charles Chapman), though hardly old enough to be in long pants, wears shining armor, while the other son, Hal (Timothée Chalamet), is a slouch who wastes his life in roistering. Anthony Lane, The New Yorker, 4 Oct. 2019
Word History
Etymology
Noun
Middle French rustre lout, alteration of ruste, from ruste, adjective, rude, rough, from Latin rusticus rural — more at rustic