The crossword solution for the term 'Weapon Caveman' is 'CLUB', which is a four-letter word. A CLUB is a primitive weapon used by cavemen, consisting of a short wooden or metal shaft with a heavy head, typically made of stone or metal. It was used as a tool for hunting and as a weapon in combat. Clubs were also used to break bones and crush skulls, making them one of the most feared weapons of the Stone Age.