First Digit of the Hand, the Thumb
Puzzle 6 of Deep Sea Journey Hard Pack
Question is: First Digit of the Hand, the Thumb
and the answer is: POLLEX
Word Meaning:
POLLEX — The thumb; the first, or preaxial, digit of the forelimb, corresponding to the hallux in the hind limb. In birds, the pollex is the joint which bears the alula or bastard wing.
Definitions from Wiktionary.