When you stamp, you step hard, either on the ground or on some object. If you're terrified of bugs, you might be tempted to stamp on a big, weird looking beetle.
You can stamp your foot when you're angry, or stamp out a small campfire after you've finished toasting marshmallows. Another way to stamp is to apply a mark or pattern to something — you might stamp your classmates' hands with ink as they enter the school dance, or stamp your return address onto an envelope. Stamp comes from Middle English, with a Germanic root — it's closely related to the German word stampfen, or "stamp with the foot."