“Aplomb” comes from the French word “à plomb,” or “according to a plumb line.” Carpenters will be more familiar with the concept of a plumb line. A plumb bob is a device that can be traced back to the engineers of ancient Egypt — it’s a cord with a pointed weight affixed to the end. When the weight is dangled, it creates a vertical line known as a “plumb line,” which was traditionally used by architects, builders, and engineers as a vertical reference point. While plumb bobs are still used, there’s been a tech upgrade: the laser level, which can project both vertical and horizontal lines hands-free.