Declension table of ?nantavya

Neuter	Singular	Dual	Plural
Nominative	nantavyam	nantavye	nantavyāni
Vocative	nantavya	nantavye	nantavyāni
Accusative	nantavyam	nantavye	nantavyāni
Instrumental	nantavyena	nantavyābhyām	nantavyaiḥ
Dative	nantavyāya	nantavyābhyām	nantavyebhyaḥ
Ablative	nantavyāt	nantavyābhyām	nantavyebhyaḥ
Genitive	nantavyasya	nantavyayoḥ	nantavyānām
Locative	nantavye	nantavyayoḥ	nantavyeṣu

Compound nantavya -

Adverb -nantavyam -nantavyāt