Your thumb is the short thick part on the side of your hand next to your four fingers.
She bit the tip of her left thumb, not looking at me.
The thumb of a glove is the part which a person's thumb fits into.
If you thumb a lift or thumb a ride, you stand by the side of the road holding out your thumb until a driver stops and gives you a lift.
It may interest you to know that a boy answering Rory's description thumbed a ride to Howth...
Thumbing a lift had once a carefree, easy-going image.
If you say that someone or something sticks out like a sore thumb or stands out like a sore thumb, you are emphasizing that they are very noticeable, usually because they are unusual or inappropriate.
Does the new housing stick out like a sore thumb or blend into its surroundings?...
In Japan a European stands out like a sore thumb.
If you say that someone is twiddling their thumbs, you mean that they do not have anything to do and are waiting for something to happen.
The prospect of waiting around just twiddling his thumbs was appalling...
The Government cannot expect graduates to twiddle their thumbs on the dole.
If you are under someone's thumb, you are under their control, or very heavily influenced by them.
I cannot tell you what pain I feel when I see how much my mother is under my father's thumb...
She has Rachel firmly under her thumb.