Henry says, ‘The Emperor, two or three years back when he was in Germany, did he not have an evil humour in his thigh? They say the weather didn't suit him. But then his dominions offer a change of climate. Whereas from one part of my kingdom to the next there is no change to be found.’
— Wolf Hall by Hilary Mantel
Does "an evil humour" mean some kind of rheumatism or pain in his thigh?
You nailed it!
The system of Ayurveda that I have learned in my professional career believes that there are three doshas that form the body. Likewise, four bodily humors were part of Shakespearean cosmology, inherited from the ancient Greek philosophers Aristotle, Hippocrates, and Galen.
The word 'evil' serves here as 'bad/ill' or maybe paining.
The OALD entry supports the term humor in this sentence:
one of the four liquids that were thought in the past to be in a person’s body and to influence health and character
Certainly, it's the pain in his thighs the author is talking about. I wouldn't have guessed it if there was no following sentences supporting it here!
Very good question +1
In this case, an "evil humour" means "an uncomfortable illness or pain." The word "evil" here is used as indicated in Merriam-Webster, definition 2 (a): causing discomfort or repulsion. Humour references the ancient theory of the humors: blood, phlegm, (yellow) bile and black bile, imbalances in which were believed to be behind virtually all illnesses. A note: from this we get the words sanguine (cheerful), choleric or bilious (ill-tempered), phlegmatic (calm), and melancholic (sad).
