the part of your hand that is shaped like a thick short finger and helps you to hold things:
a baby sucking its thumb
She held the coin carefully between finger and thumb.
the part of a glove that fits over your thumb
3 British English be all thumbs American English informal
to be unable to do something in which you have to make small careful movements with your fingers:
Would you do up these buttons for me? I seem to be all thumbs today.
when an idea or plan is officially accepted or not accepted:
The project was finally given the thumbs up.
Her performance got the thumbs down from the critics.
to be so strongly influenced by someone that they control you completely:
He was still under his father's thumb.