thumb, also called pollex, short, thick first digit of the human hand and of the lower-primate hand and foot. It differs from other digits in having only two phalanges (tubular bones of the fingers and toes).

What part of the body is the pollex?

When a person is standing in the medical anatomical position (where the palm is facing to the front), the thumb is the outermost finger. The Medical Latin English noun for thumb is pollex (compare hallux for big toe), and the corresponding adjective for thumb is pollical.

What digit number is your pollex?

from The Century Dictionary.

noun In anatomy, the innermost digit of the hand or foot, when there are five; the thumb or the great toe, especially the thumb, the great toe being usually distinguished as pollex pedis, or hallux.