A dagger is a short knife with a sharp point designed for stabbing. Unlike a regular knife meant for cutting food or rope, a dagger has a blade sharp on both edges and comes to a dangerous point, making it effective as a weapon. Daggers have been used throughout history by soldiers and sailors who needed a compact weapon they could carry easily.

In ancient Rome, senators concealed daggers under their togas. Medieval knights wore ornate daggers at their belts as backup weapons. Pirates kept daggers tucked in their boots. Because daggers are small and easy to hide, they appear frequently in stories involving betrayal or secret plots.

Today, the word dagger describes other pointed things too. In printing, a dagger symbol (†) marks footnotes. If someone looks daggers at you, they're glaring with hostile eyes. And when you say someone's cruel words felt like a dagger in the heart, you mean those words caused sharp, stabbing emotional pain.