opposable thumb

American  

[uh-poh-zuh-buhl thuhm] / əˈpoʊ zə bəl ˈθʌm /

noun

1. Anatomy, Zoology. a thumb that can move independently of the other fingers on the same hand, allowing the thumb to touch the other fingers and work with them to handle, grasp, and grip objects, a feature that is characteristic of primates.

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opposable thumb Scientific  

/ ə-pō′zə-bəl /

1. A thumb that can be placed opposite the fingers of the same hand. Opposable thumbs allow the digits to grasp and handle objects and are characteristic of primates.

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opposable thumb Cultural  

1. A thumb that can be used for grasping.

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Discover More

Opposable thumbs are one of the distinguishing features of primates.

The opposable thumb of human beings allows us to use tools.

Example Sentences

The Rwanda trip, Mr. Attenborough says, wasn’t supposed to be about gorillas at all, but rather the opposable thumb, one of the significant characteristics we share with the great apes.

From The Wall Street Journal • Apr. 17, 2026

“A thumb, yes, because the opposable thumb is what differentiates us from beasts.”

From New York Times • Jan. 21, 2024

Sprouting from your palm are four fingers and an opposable thumb.

From Salon • Sep. 21, 2022

Our flexible opposable thumb is used more and more for texting on our smartphones, and our straight fingers are spending hours typing while we stare at screens.

From Slate • Dec. 17, 2015

We have five fingers, including one opposable thumb.

From "Cosmos" by Carl Sagan