friendyoudaoicibaDictYouDict[friend 词源字典]
friend: [OE] Etymologically, friend means ‘loving’. It and its Germanic relatives (German freund, Dutch vriend, Swedish frände, etc) go back to the present participle of the prehistoric Germanic verb *frijōjan ‘love’ (historically, the German present participle ends in -nd, as in modern German -end; English -ng is an alteration of this). *Frijōjan itself was a derivative of the adjective *frijaz, from which modern English gets free, but which originally meant ‘dear, beloved’.
=> free[friend etymology, friend origin, 英语词源]
friend (n.)youdaoicibaDictYouDict
Old English freond "one attached to another by feelings of personal regard and preference," from Proto-Germanic *frijand- "lover, friend" (cognates: 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" (see free (adj.)).

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.
friend (v.)youdaoicibaDictYouDict
in the Facebook sense, attested from 2005, from the noun. Friend occasionally has been used as a verb in English since c. 1200 ("to be friends"), though the more usual verb for "join in friendship, act as a friend" is befriend. Related: Friended; friending. Old English had freonsped "an abundance of friends" (see speed (n.)); freondleast "want of friends;" freondspedig "rich in friends."