|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.
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.