The Tocharian B word śāśvat
Word śāśvat
ɕ a ɕ v ɐ t
IPA ɕaɕvɐt
Meaning everlasting

Comments
Douglas Q. Adams, “Etymological Dictionary of Tocharian B”, 1999, Brill

Other words that might be of interest
ente ‘when’, pikul ‘year’, ompostäṃ ‘afterwards’, postäṃ ‘after’, ṣek ‘always’, manta ‘never’, ṣe-keś ‘once only’