opposable thumb

Science Dictionary
opposable thumb   (ə-pō'zə-bəl)  Pronunciation Key 
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.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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American Heritage
Cultural Dictionary

opposable thumb definition

A thumb that can be used for grasping.

Note: Opposable thumbs are one of the distinguishing features of primates.
Note: The opposable thumb of human beings allows us to use tools.
The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
Cite This Source
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