What is (a) To form a scarf on the end or edge of, as for a joint in timber, metal rods, etc. (b) To unite, as two pieces of timber or metal, by a scarf joint called?

scarf — (a) To form a scarf on the end or edge of, as for a joint in timber, metal rods, etc. (b) To unite, as two pieces of timber or metal, by a scarf joint. (Webster's 1913.)