What is "ball of the thumb"

n. 1 (context anatomy informal English) The fleshy portion, opposite the nail, of the first segment (first phalange) of the human thumb. 2 (context anatomy English) The most fleshy portion of the palm of the human hand, located adjacent to the second joint of the thumb: the thenar eminence.

Ball of the thumb may be:

• Thenar eminence, most fleshy portion of the palm of the human hand, located adjacent to the second joint of the thumb
• Fleshy portion (opposite the nail), of the first segment (first phalange) of the human thumb