Prehensility
Prehensility is the quality of an organ that has adapted for grasping or holding. Examples of prehensile body parts include the tails of New World monkeys and opossums, the trunks of elephants, and the proboscises of tapirs. Contrary to popular myth, the penis of the dolphin is not prehensile. Logically this should apply to hands as well but this would not be normal usage of the word.
The word is derived from the Latin term prehendere, meaning "to grasp."