In a fussy manner; with excessive concern about small, unimportant details.
From English fussy (expressing concern over trivial matters) plus -ly adverbial suffix. Fussy itself likely derives from uncertain origin, possibly connected to 'fuss' (commotion).
Someone who arranges their pencils by height and straightens picture frames constantly is acting fusilly—it's the adverb form that describes that particular way of being particular!
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