Gesundheit

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from German Gesundheit ‘health’.

wiktionary

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From German Gesundheit(literally “health”), from gesund(“healthy”). The adjective is cognate with English sound, from Old English ġesund(“sound, safe, healthy”).

etymonline

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gesundheit (interj.)

1914, from German Gesundheit, literally "health!", from Old High German gisunt, gisunti "healthy" (see sound (adj.)). Also in the German toast auf ihre Gesundheit "to your health." God bless you after someone sneezes is credited to St. Gregory the Great, but the pagan Romans (Absit omen) and Greeks had similar customs.