Definition - lever: A rigid bar resting on a pivot, used to help move a heavy or firmly fixed load with one end when pressure is applied to the other. The ways in which one can use mechanical advantage in the form of a lever are near infinite.. from the simplicity of a hammer pulling a nail, to the immense force created by a well placed Birk bar, there’s simply no great knowledge in the field of construction that will aid in making hard, heavy and dangerous tasks easy and safe. Never stop expand