#1 exacting a. [fastidious] having complicated nutritional requirements; especially growing only in special artificial cultures; "fastidious microorganisms"; "certain highly specialized xerophytes are extremely exacting in their requirements". wn
#2 exacting s. [stern, strict] severe and unremitting in making demands; "an exacting instructor"; "a stern disciplinarian"; "strict standards". wn
#3 exacting s. [exigent] requiring precise accuracy; "an exacting job"; "became more exigent over his pronunciation". wn
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