A sharpener is a tool that restores a dull blade or point to sharpness by grinding or scraping away material. The most familiar type is a pencil sharpener, which uses a small blade to shave wood and graphite into a fine point. You insert your pencil, twist it around, and pencil shavings curl off into the container below.

Kitchen knife sharpeners work differently but serve the same purpose: they grind the blade's edge against hard materials like stone or steel to remove tiny amounts of metal and restore the cutting edge. A chef might run a dull knife along a sharpening steel before slicing vegetables, or use a whetstone to carefully sharpen a blade that's lost its edge.

Sharpening matters because sharp tools work better and are actually safer than dull ones. A sharp knife cuts cleanly through a tomato, while a dull knife slips and slides dangerously. A sharp pencil makes neat, precise lines, while a dull one smudges and breaks.

The word can describe the tool itself (a pencil sharpener on your desk) or the person doing the work (the knife sharpener who visits restaurants to maintain their kitchen equipment).