Middle English ost, host "person who receives guests, guest," borrowed from Anglo-French oste, hoste, going back to Latin hospit-, hospes "guest, visitor, person receiving guests," going back to dialectal Indo-European *ghosti-pot- (whence probably also Old Church Slavic gospodĭ "lord, master"), from *ghost-i- "outsider, guest" + *pot- "one in control, master" — more at guest entry 1, potent entry 1
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