Old English freond "one attached to another by feelings of personal regard and preference," from Proto-Germanic *frijōjands "lover, friend" (source also of Old Norse frændi, Old Danish frynt, Old Frisian friund, Dutch vriend, Middle High German friunt, German Freund, Gothic frijonds "friend"), from PIE *priy-ont-, "loving," present-participle form of root *pri- "to love."
Meaning "a Quaker" (a member of the Society of Friends) is from 1670s. Feond ("fiend," originally "enemy") and freond often were paired alliteratively in Old English; both are masculine agent nouns derived from present participle of verbs, but they are not directly related to one another (see fiend). Related: Friends.
prī-, Proto-Indo-European root meaning "to love." In some languages (notably Germanic and Celtic) it developed derivatives with the sense "free, not in bondage," perhaps via "beloved" or "friend" being applied to the free members of one's clan (as opposed to slaves).
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit priyah "own, dear, beloved," priyate "loves;" Old Church Slavonic prijati "to help," prijatelji "friend;" Welsh rhydd "free;" Old English freo "exempt from; not in bondage, acting of one's own will," Gothic frijon "to love," Old English freod "affection, friendship, peace," friga "love," friðu "peace," Old Norse Frigg, name of the wife of Odin, literally "beloved" or "loving."