Declension table of ?tvacana

Neuter	Singular	Dual	Plural
Nominative	tvacanam	tvacane	tvacanāni
Vocative	tvacana	tvacane	tvacanāni
Accusative	tvacanam	tvacane	tvacanāni
Instrumental	tvacanena	tvacanābhyām	tvacanaiḥ
Dative	tvacanāya	tvacanābhyām	tvacanebhyaḥ
Ablative	tvacanāt	tvacanābhyām	tvacanebhyaḥ
Genitive	tvacanasya	tvacanayoḥ	tvacanānām
Locative	tvacane	tvacanayoḥ	tvacaneṣu

Compound tvacana -

Adverb -tvacanam -tvacanāt