Buttress
BUT'TRESS, noun [This word appears to be composed of but, end, and truss, or some word of that family.]
1. A prop; a wall or abutment built archwise, serving to support another wall on the outside, when very high or loaded with a heavy superstructure.
2. Any prop or support.
BUT'TRESS, verb transitive To support by a buttress; to prop.