Did you know that the above word originated first with the Latin cara (face) and then the French chere (face). It became to mean "mood, frame of mind". Because cheer was used with mostly happy moods it became a word meaning "joy, mirth".
It was first used in literature as a shout of "Cheers!" in Daniel Defoe's book, 'Captain Singleton', "We gave them a Chear, as the seamen call it."
Don't you think it is strange how words change their meanings over time?