From Proto-Germanic*swēsaz(“one's own, familiar, trusted”), *swēsa- ‘own, relation’, from Proto-Indo-European. Cognate with Old Frisian swēs ‘related’, Old Saxon swās ‘dear’, Old Norse sváss ‘dear, trusty’, Gothic 𐍃𐍅𐌴𐍃 ‘own’. The Indo-European root is also the source of Latin sibi, Russian себя.