harbinger..................

The original meaning of harbinger in the 12th century was a lodging-house keeper. The word derives from 'harbourer' or, as they spelled it then, 'herberer' or 'herberger' , i.e. one who harbours people for the night. 'Herberer' derives from the French word for 'inn' - 'auberge'. 'Ye herbergers' are referred to (as common lodging-house keepers) in the Old English text The Lambeth Homilies, circa 1175.

By the 13th century, 'harbinger' had migrated from its original meaning of lodging keeper, to refer to a scout who went ahead of a military force or royal court to book lodgings for the oncoming horde. This is the source of the 'advance messenger' meaning that we understand now.

Harbingers could also act as foragers and information gatherers, since they often made first contact with the enemy force by clashing with its harbingers. Because encountering opposing harbingers could reveal a foe's location and direction, commanders sometimes ordered their own harbingers to ride away from the army's line of march, thereby deceiving the enemy as to the army's position and the commander's intentions.

We now use 'harbinger' in a metaphorical sense, meaning 'forerunner; announcer'. We sometimes hear of 'harbingers of Spring', or 'harbingers of day', but it is the 'harbingers of doom' that are the busiest in our present-day language.
 
There is also a computer game with the name...