बहुवर्षसहस्रिन्bahuvarṣasahasrinmfn. id., many thousand years old ib.
masculine, feminine and neuter; or adjective the same, many thousand years old ibidem
कोशःDictionaries
Every entry for a word in Apte, Monier-Williams, Macdonell and the Dhātupāṭha, with their abbreviations spelled out, and an analysis of its forms.