Definitions

1. noun

the first digit on the hand, especially the outermost digit, which is opposite the little finger.

“She hurt her thumb while gardening.”

2. verb

to press or operate something with the thumb, typically a button or control.

“She thumbed the button to turn on the music.”

3. verb

to travel or go somewhere, especially on foot, by thumbing a ride from a passing vehicle.

“He thumbed his way across the country.”