ग्रह-वृ-दृ-निश्चिगमश् च

This debars घञ्; and in the case of निश्चि the affix अच् is debarred. As ग्रहः 'a planet'; वरः 'a boon'; दरः 'tearing, a cave'; निश्चयः 'certainty'; गमः 'march'.

The verb निश्चि would have taken अच्, but takes अप् which causes difference of accent.

Vart:-The roots वश् and रण् should also be included in this; as वशः 'obedient'; रणः 'battle'.

Vart:- When the sense is that of घञ्, the affix क is directed to be employed, after the following verbs :- स्था, स्ना, पा, व्यध्, हन् and युध् । As प्रस्थः 'a table-land' (on which they move); प्रस्नः 'a vessel for bathing' (in which they bathe); प्रपाः 'a place where water is distributed to travellers' (that out of which they drink); आविधः 6.1.16 'an awl, a drill' (that by which they pierce); विघ्नः 'an obstacle' (in which they are obstructed); आयुधः 'battle' (where they fight).,