whetstone

A whetstone is a stone used to sharpen the edge of a knife, razor, chisel, or other blade. It works by wearing away a small amount of metal so the edge becomes finer and sharper. Some are used with water, others with oil, and they come in different grades from rough to very fine.

Most of the time, the word refers to the actual sharpening stone itself, not to the verb whet. If you picture someone carefully drawing a kitchen knife across a flat stone to bring the edge back, you have the heart of the meaning.

A whetstone is a sharpening stone, usually flat, used to put a better edge on blades and other cutting tools. People use whetstones for kitchen knives, pocket knives, razors, scissors, chisels, and similar tools. As the blade moves across the stone at a steady angle, the rough surface removes tiny bits of metal and smooths the edge. Coarser stones shape a dull or damaged edge, while finer stones polish and finish it.

Traditionally, whetstones were made from natural stone. Today, many are made from man-made abrasive materials as well. Some are called water stones because they are used with water, and others are oil stones because they are used with oil. In everyday English, this is the main meaning of the word: a practical tool for sharpening.

The word is related to the verb whet, which means "sharpen" and, by extension, "make someone eager for something," as in whet your appetite. But that figurative sense belongs to the verb whet, not usually to the noun whetstone. So when you see whetstone, think first of the stone in the hand, the careful sharpening motion, and the return of a clean, sharp edge.