To slap means to hit someone or something with the flat part of your hand, making a sharp, loud sound. If you slap a mosquito on your arm, you hit it quickly with your palm. A slap stings more than it injures, and that distinctive smacking sound is part of what makes it different from a punch or a shove.

Slapping someone is generally considered rude and aggressive, though context matters. You might playfully slap your forehead when you suddenly remember something you forgot, or slap your knee while laughing at a funny joke. In hockey, players slap the puck with powerful shots called slap shots. You might also slap a high-five with a friend after scoring a goal.

The word can also mean to put something down forcefully and carelessly, like when someone slaps their homework onto the teacher's desk. When something happens quickly or carelessly, we sometimes use slap: a painter might slap paint on a wall without being neat about it, or someone might slap together a last-minute costume for a school play.