"fastidiously" in the adverb sense
1. painstakingly, fastidiously
in a fastidious and painstaking manner
"it is almost a waste of time painstakingly to learn the routines of selling"
in a fastidious manner
"he writes extremely musical music, of which the sound is fastidiously calculated and yet agreeably spontaneous and imaginative"
Source: WordNet® (An amazing lexical database of English)
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