From Longman Dictionary of Contemporary Englishthumbthumb1 /θʌm/ ●●● S3 noun [countable] 1 
HBHthe 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 DCCthe part of a glove that fits over your thumb3 → be all fingers and thumbs4 → the thumbs up/down5 → be under somebody’s thumb → rule of thumb at rule1(8), → stand/stick out like a sore thumb at sore1(6)
HBHthe 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 DCCthe part of a glove that fits over your thumb3 → be all fingers and thumbs4 → the thumbs up/down5 → be under somebody’s thumb → rule of thumb at rule1(8), → stand/stick out like a sore thumb at sore1(6)Examples from the Corpus
thumb• But it was plainly calculated as a thumb in the eye of the United States.• Then he looked at Bill Wall, extending his hand with finger and thumb crooked.• The third had a grotesquely enlarged thumb.• She put the mustache back and pressed it with her thumb.• I sat there and twiddled my thumbs.• As a rule of thumb, funds with durations of one to three years are relatively conservative.• When constructing a footpath we follow rules of thumb.thumbthumb2 verb 1 → thumb a lift2 → thumb your nose at somebody/something → thumb through something→ See Verb tableExamples from the Corpus
thumb• Two or three cars passed me and I tried to thumb a lift, but they didn't stop.• Faubus had again thumbed his nose at the judiciary by refusing to appear.• Voters here have always been drawn to against-the-grain outsiders who make a career of thumbing their noses at party traditionalists.• She thumbed them into the magazine before placing it carefully back in the box with the weapon.• Once again Azadi thumbed through the intelligence report for some inspiration.• As a joke I actually bought it for Richard to thumb through.Origin thumb1 Old English thuma 