"Suddenly there was with the angel a multitude of the heavenly host praising God" (Luke 2:13): modern readers picture a party host, not an army of angels.

Luke 2:13 describes "a multitude of the heavenly host" appearing to the shepherds. Read with modern ears, "host" sounds like the angels are throwing a party. In the KJV it's a military word meaning an army, a body of troops drawn up for battle. That's the same "hosts" in "the LORD of hosts," one of the Bible's most common divine titles, literally "commander of armies."

The word traces to Latin hostis ("army," originally "enemy") by way of Old French. English later split the word in two: the guest-receiving sense of "host" (from a different Latin root, hospes) became the everyday meaning, while the older army sense survived mostly in biblical and liturgical language, which is exactly why it now misleads readers.