shear

To shear something is to cut it cleanly, often in one quick motion; think of taking wool off a sheep. But "shear" is not just a farm word. It can also mean to break off because of pressure, like a metal bolt that shears when a machine is pushed too hard. You may also hear about "wind shear," which is a sudden change in wind speed or direction. At its core, the word is about cutting, breaking, or being pulled apart by force.

The word "shear" has several related meanings, and they all center on the idea of cutting, sliding apart, or breaking because of force. Most often, it means cutting wool from a sheep with large scissors called shears. "The shepherd sheared the sheep in spring." This is the most familiar picture of the word: a clean, quick cut that removes a layer from something.

However, "shear" goes far beyond farming. In engineering and physics, it can describe a force that makes one part of something slide past another. Scissors are a simple example: they use this kind of force to cut paper. A bolt, pin, or other part may also shear off under heavy stress, meaning it snaps because of sideways pressure. "The bolt sheared off during the earthquake." In weather, "wind shear" means a sudden change in wind speed or direction, and that can be dangerous for aircraft.

The word also appears in a few other areas. The past form shorn is often used when something has been cut away or taken off, especially hair, wool, or even power in a figurative sense. In mathematics, a shear transformation changes a shape by pushing one part sideways so that, for example, a rectangle becomes a parallelogram. Whether it involves wool, metal, wind, or shape, "shear" usually points to cutting, sideways force, or something breaking along a line.