harbingeryoudaoicibaDictYouDict[harbinger 词源字典]
harbinger: [12] Originally, a harbinger was simply someone who provided ‘harbour’ – that is, ‘shelter, lodging’. The word began life as a derivative of Old French herberge ‘lodging’, a borrowing from heriberga, the Old Saxon equivalent of Old English herebeorg (whence modern English harbour). English acquired it as herbergere, and the n did not put in an appearance until the 15th century (it was quite a common phenomenon, seen also in messenger and passenger).

As for its meaning, it developed in the 14th century to ‘someone sent on ahead to arrange for lodging for an army, an official royal party, etc’, and from this came the present-day figurative sense ‘forerunner’.
=> harbour[harbinger etymology, harbinger origin, 英语词源]
harbinger (n.)youdaoicibaDictYouDict
late 15c., herbengar "one sent ahead to arrange lodgings" (for a monarch, an army, etc.), alteration of Middle English herberger "provider of shelter, innkeeper" (late 12c.), from Old French herbergeor "one who offers lodging, innkeeper," agent noun from herbergier "provide lodging," from herber "lodging, shelter," from Frankish *heriberga "lodging, inn" (cognate with Old Saxon, Old High German heriberga "army shelter"), from Germanic compound *harja-bergaz "shelter, lodgings," which is also the source of harbor (n.). Sense of "forerunner, that which precedes and gives notice of the coming of another" is mid-16c. Intrusive -n- is 15c. (see messenger). As a verb, from 1640s (harbinge "to lodge" is late 15c.).