प्रमद-सम्मदौ हर्षे

As कन्यानां प्रमदः 'the joy of girls'; कोकिलानां सम्मदः 'the rejoicing of cuckoos'.

Why do we say 'when meaning delight'? Observe प्रमादः 'carelessness'; सम्मादः 'frenzy'.

Instead of saying 'the verb mad preceded by pra and sam takes the affix ap' which also would have given the above forms, the full forms have been used in the sutra to indicate that these words are रूढि in this sense; for the sense of the root is not visible in these words.,