The affix a is also added to the word amāvāsyā in the sense of 'born therein'.,
This adds a third affix to the वुन् and अण् already given. Thus अमावास्यः, अमावास्यकः, आमावास्यः ॥ So also after the word अमावस्य, as अमावस्यः, अमावस्यकः and आमावस्यः ॥,
अ च
Adhyāya 4 · Pāda 3 · Rule 31