Declension table of ?siddhāntasamāsa

Masculine	Singular	Dual	Plural
Nominative	siddhāntasamāsaḥ	siddhāntasamāsau	siddhāntasamāsāḥ
Vocative	siddhāntasamāsa	siddhāntasamāsau	siddhāntasamāsāḥ
Accusative	siddhāntasamāsam	siddhāntasamāsau	siddhāntasamāsān
Instrumental	siddhāntasamāsena	siddhāntasamāsābhyām	siddhāntasamāsaiḥ siddhāntasamāsebhiḥ
Dative	siddhāntasamāsāya	siddhāntasamāsābhyām	siddhāntasamāsebhyaḥ
Ablative	siddhāntasamāsāt	siddhāntasamāsābhyām	siddhāntasamāsebhyaḥ
Genitive	siddhāntasamāsasya	siddhāntasamāsayoḥ	siddhāntasamāsānām
Locative	siddhāntasamāse	siddhāntasamāsayoḥ	siddhāntasamāseṣu

Compound siddhāntasamāsa -

Adverb -siddhāntasamāsam -siddhāntasamāsāt