In a somewhat fumish or fume-like manner; in a way that is rather smoky or vapor-filled (archaic/rare).
From 'fumish' (adjective) plus the adverbial suffix '-ly,' creating a double-stacked diminishing form meaning 'somewhat in a fume-like way.'
This is a word within a word within a word—fume→fumish→fumishly—showing how Old and Middle English loved layering suffixes until they created wonderfully specific but rarely-used terms.
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