THUMB

• thumb [countable]
• 1 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.
• 2 the part of a glove that fits over your thumb
• 3

  be all fingers and thumbs

  British English be all thumbsAmerican 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.
• 4

  the thumbs up/down

  informal 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.
• 5

  be under somebody's thumb

   to be so strongly influenced by someone that they control you completely:
• He was still under his father's thumb.

• ➔ rule of thumb

  at rule1 (8)

  ; ➔ stand/stick out like a sore thumb

  at sore1 (6)

Definition from the Longman Dictionary of Contemporary English
Advanced Learner's Dictionary.