All 9 Uses

however
in
Black: The Birth of Evil
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Several of the vaccines, however, would be subjected to a whole new gamut of rigorous testing procedures if Congress passed the new legislation introduced by Merton Gains before he became deputy secretary of state.†
Chpt 8

however = a word used to connect contrasting ideas as when using though, in spite of that, in contrast, nevertheless, etc.
There in Denver, however, he had no explanation for how he could be dreaming about the Raison Strain, especially since the related events hadn't happened yet.†
Chpt 9
There was the possibility, however remote, that he was different from Rachelle.
Chpt 22

however = regardless of how
Let's just say the incident in Bangkok has exposed the possibility, however slight, that the vaccine may not be stable.
Chpt 24 *
By midday, however, he felt as though he must go somewhere by himself to consider the events continuing to nag his mind.†
Chpt 32 *

however = a word used to connect contrasting ideas as when using though, in spite of that, in contrast, nevertheless, etc.
Spend a few days in that reality, a week, a month, however much time you need.
Chpt 35

however = whatever amount of
He could feel however he wanted to in a dream.†
Chpt 8 *
MONIQUE WATCHED Thomas pace and wondered if there was any way, however unlikely, that the tale he'd spun over the past two hours was anything more than absolute nonsense.†
Chpt 18
They are like Roush, but you may think of me however you want now.†
Chpt 22

Definitions:

(1) (however as in: However, complications may...)
though (or another expression that connects contrasting ideas)

Based on idea 1 we might not expect idea 2, but this is a way of saying that even though idea 1 exists, we still have idea 2. Synonyms include in spite of that, despite that, nevertheless, nonetheless, on the other hand, in contrast and but.
(2) (however as in: However much she tried...)
to whatever degree (regardless of how much; or whatever unspecified amount)
(3) (however as in: However you do it, get it done!)
in whatever way
(4) (meaning too rare to warrant focus)
Much more rarely (and arguably incorrectly), however can be used to intensify the word how, as when one says "However did you find her?" Grammarians would suggest using two words for that usage: "How ever did you find her?"