Saying the phrase billiards cue is tautological, because a billiard in French referred to both the popular game "pool" and the stick used to play pool. That later definition is more important, for as we move back to the Old French word bille, it just means "stick". So, basically, a game of billiard is just a game of "sticks", which sort of makes sense. Earlier on, the word bille was much larger in size, actually meaning "tree trunk", from Latin billa, with the same meaning. This in turn is unknown in derivation, but etymologists theorize it is Gaulish in origin, which would geographically bring us back to France. It is thought that this is in fact Gaulish because Gaulish is a Celtic language, and there is a Proto-Celtic term sounding like belyos, which meant "tree" as well. In any case, the word jumped that obscure period and most likely ultimately comes from the Proto-Indo-European root bhleh, meaning "blossom", under the connection of another living plant.
Adam Aleksic has been described as the internet's sixth most famous etymologist. He loves writing about himself in the third person, he's a freshman at Harvard University, and he has disturbing interests in linguistics, vexillology, geography, board games, limericks, and law.
The Etymology Nerd