स नपुंसकम्

It, namely the द्विगु or द्वन्द compound, with regard to which singular number has been ordained by the above rules, is always neuter gender.
As, दशगवम् 'an aggregate of ten cows,' पाणिपादम् 'hands and feet.' शिरोग्रीवम् 'head and neck.'

This sutra debars the operation of the rule by which a compound gets the gender of its subsequent member. See 2.4.26.

Vart:- A Dvigu, the last member of which ends in short अ, is employed in the feminine gender only; as पञ्चपूली, दशरथी.

Vart:- A Dvigu, the last member of which is a feminine word ending in आप् affix, is optionally feminine; as, पञ्चखट्वम् or पञ्चखट्वी.

Vart:- A Dvigu, the last member of which is a word ending in अन्, is optionally feminine and the न is elided : as पञ्चतक्षम् or पञ्चतक्षी.

Vart:- A Prohibition must be stated in the case of Dvigu compounds ending in पात्र &c., पञ्चपात्रम्; चतुर्युगम्; त्रिभुवनम्.