The Compendium of Caraka 3.8.54_1

3.8.54_1

tatra nyūnaṃ---pratijñāhetūdāharaṇopanayanigamanānāmanyatamenāpi nyūnaṃ nyūnaṃ bhavati; yadvā bahūpadiṣṭahetukamekena hetunā sādhyate tacca nyūnam/

Among them, the deficient: it is deficient if it is lacking even in one among the proposition, reason, example, application, and conclusion; or when a thesis taught with many reasons is substantiated with only one reason, that too is deficient.