thumb

A thumb is the part of your hand that looks like a short, fat finger. Most people have a thumb on each hand.

Example: In many countries, pointing your thumb up means, "good".

A thumb or thumbnail is a small picture on a computer that you can click on to see a larger picture.

If someone thumbs something, they touch it with the thumb.

When someone thumbs, they are standing by a road waiting for someone to give them a ride.

Example: I thumbed down a pickup truck to take me to San Antonio.