The affix knu comes after the verbs - 1. tras 'to tremble' 2. gṛdh 'to be greedy' 3. dhṛṣ 'to be bold' 4. kṣip 'to throw' in the sense of 'agent having such a habit etc.'.,
As, त्रस्नुः 'trembling'; गृध्नुः 'greedy'; धृष्णुः 'bold'; and क्षिण्नुः 'throwing'.,