An Etymological Dictionary of the German Language/Annotated/sein

by Friedrich Kluge

sein, possessive pronoun, ‘his, its,’ from Middle High German and Old High German (also Old Saxon) sîn; compare Gothic seins, ‘his’; allied to Gothic si-k, ‘himself,’ formed with the possessive suffix -îna- like mein and dein. Compare sich; the further discussion of the word belongs to grammar.

sein, anomal. verb; its tenses are formed from various stems. The Teutonic primary stems are es, -s, with the same meaning (Old High German, Middle High German, and Modern High German ist, Old High German and Middle High German sint, Modern High German sind; subj. mood, Old High German and Middle High German sî, Modern High German sei; infinitive Middle High German sîn, Modern High German sein; compare Gothic 3rd personal singular ist, plu. sind; optative sijau; Anglo-Saxon and English 3rd personal singular is, 3rd personal plural Anglo-Saxon sind); corresponding to the Aryan root es in Latin es-t, Greek ἐστί, Sanscrit ás-ti, Latin sunt, sîm, Sanscrit sánti, &c. The second stem begins with b, Modern High German, Middle High German, and Old High German bin, Old Saxon bium, Anglo-Saxon beó, ‘I am’ (Anglo-Saxon also ‘I shall’), connected with the stem of Latin fio, Greek φύω, Sanscrit bhû, ‘to become.’ For the third stem (of gewesen and war) see under Wesen. Further details belong to grammar.