The word was already part of English before the Norman Conquest. Its first dated appearance is in the Ancrene Riwle, a guide written for women choosing a life of religious seclusion, in 1230, describing treacherous advice.
Old Saxon had a closely related word for deceit. Old High German also had its own word to describe deceit, and that German word is the ancestor of the modern German word Fehde, used for a long-running family dispute.
Behind the word lay a Proto-Germanic root, *faihaz, meaning 'hostile, or deceptive'. It may trace to the same ancient source as Sanskrit pisunah, meaning 'malicious'.
FOE and FEUD share the same root. FOE is native to Old English, originally meaning an adversary in a blood feud. FEUD entered English around 1300, from a Germanic word meaning enmity, or hostility, around the same time this word's own harsh edge was just beginning to soften.
By the late thirteenth century the word had softened from outright treachery into something more like unpredictability, especially of Fortune, or of a person’s own loyalty. Shakespeare gave the sense its most famous line, in Romeo and Juliet: ‘all men call thee...’. A related Middle English verb, meaning to deceive, later came to mean something quite different, to confuse or bewilder someone, a sense that survived long enough to appear in the novels of Sir Walter Scott.
