Declension table of ?śirastra

Neuter	Singular	Dual	Plural
Nominative	śirastram	śirastre	śirastrāṇi
Vocative	śirastra	śirastre	śirastrāṇi
Accusative	śirastram	śirastre	śirastrāṇi
Instrumental	śirastreṇa	śirastrābhyām	śirastraiḥ
Dative	śirastrāya	śirastrābhyām	śirastrebhyaḥ
Ablative	śirastrāt	śirastrābhyām	śirastrebhyaḥ
Genitive	śirastrasya	śirastrayoḥ	śirastrāṇām
Locative	śirastre	śirastrayoḥ	śirastreṣu

Compound śirastra -

Adverb -śirastram -śirastrāt