The Tocharian B word postäṃ
Word postäṃ
p o s t ə ṃ
IPA postəṃ
Meaning after

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

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