I know that Uncle Tom's Cabin is full of neologisms, and I try my best to grit my teeth and infer as best I can without racing down every such rabbit hole that presents itself, but with rhumatis, for whatever reason, I can't quell my curiosity. I must figure out what it means (if anything). The passage for context, from Chapter 10:
"Now," said Aunt Chloe, bustling about after breakfast, "I must put up yer clothes. Jest like as not, he'll take 'em all away. I know thar ways—mean as dirt, they is! Wal, now, yer flannels for rhumatis is in this corner; so be careful, 'cause there won't nobody make ye no more.
What is rhumatis supposed to mean here? Given that flannels are usually warm, I'm curious if its something to do with the outdoors. Or perhaps its some kind of phonetic neologism? Can't think of any words that sound anything like rhumatis though.