guestyoudaoicibaDictYouDict[guest 词源字典]
guest: [13] Guest comes ultimately from the same source as produced host. Their family tree diverged in prehistoric times, but their close relationship is pointed up by the fact that the related French hôte means both ‘guest’ and ‘host’. The common ancestor was Indo- European *ghostis ‘stranger’, whose Germanic descendant *gastiz produced German and Dutch gast, Swedish gäst, Danish gæst, and English guest.

The Old English version of the word was giest, which would have produced modern English *yest, but it was elbowed out in Middle English times by Old Norse gestr. The spelling gu-, indicating a hard /g/ sound, developed in the 16th century.
=> host, xenophobia[guest etymology, guest origin, 英语词源]
guest (n.)youdaoicibaDictYouDict
Old English gæst, giest (Anglian gest) "an accidental guest, a chance comer, a stranger," from Proto-Germanic *gastiz (cognates: Old Frisian jest, Dutch gast, German Gast, Gothic gasts "guest," originally "stranger"), from PIE root *ghos-ti- "stranger, guest; host" (cognates: Latin hostis, in earlier use "a stranger," in classical use "an enemy," hospes "host," from *hosti-potis "host, guest," originally "lord of strangers;" Greek xenos "guest, host, stranger;" Old Church Slavonic gosti "guest, friend," gospodi "lord, master"); the root sense, according to Watkins, probably is "someone with whom one has reciprocal duties of hospitality," representing "a mutual exchange relationship highly important to ancient Indo-European society." But as strangers are potential enemies as well as guests, the word has a forked path.

Spelling evolution influenced by Old Norse cognate gestr (the usual sound changes from the Old English word would have yielded Modern English *yest). Meaning "person entertained for pay" (at an inn, etc.) is from late 13c. Old English also had cuma "stranger, guest," literally "a comer." Phrase be my guest in the sense of "go right ahead" first recorded 1955.
guest (v.)youdaoicibaDictYouDict
early 14c., "receive as a guest;" 1610s, "be a guest;" 1936, American English, "appear as a guest performer," from guest (n.). Related: Guested; guesting.