The Tocharian B word ṣer
Word ṣer
ʂ e r
IPA ʂer
Meaning sister
See also Proto-Indo-European: *swésōr ‘sister’

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

Other words that might be of interest
klyiye ‘woman’, śana ‘woman’, eṅkwe ‘man’, śaumo ‘man’, śamaśke ‘child’, petso ‘husband’, mācer ‘mother’, pācer ‘father’, kālyśke ‘boy’, procer ‘brother’, tkācer ‘daughter’, tsaṣke ‘elder’, stere ‘elder’, gottär ‘family’, klaiññe ‘female’, śamñāṃśka ‘girl’, āwe ‘grandfather’, orotstse-pācer ‘grandfather’, śāmñe ‘human, mortal’, pets ‘husband’, amārraṣṣe ‘immortal’, oṅkrotte ‘immortal’, onuwaññe ‘immortality’, eṅkwaññe ‘male’, enkwe ‘male’, ammakki ‘mother’, aśiya ‘nun’, soy ‘son’