a. Oppressive or unreasonably severe in making demands or requiring the exact fulfillment of obligations; harsh; severe. “A temper so exacting.” T. Arnold -- Ex*act"ing*ly, adv. -- Ex*act"ing*ness, n. [ 1913 Webster ]
(adj) having complicated nutritional requirements; especially growing only in special artificial cultures, Syn. exacting, Ant. unfastidious, Example:fastidious microorganisms; certain highly specialized xerophytes are extremely exacting in their requirements