pollex

The movable joint of the forceps of the lobster, crawfish, or crab; a dactylopodite.

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.

In zoology: The innermost digit of the fore limb only, when there are five; the digit that corresponds to the human thumb.

The thumb of a bird; the short digit bearing the alula or bastard wing, regarded as homologous with either the human thumb or the forefinger.

The first, or preaxial, digit of the fore limb, corresponding to the hallux in the hind limb; the thumb. In birds, the pollex is the joint which bears the bastard wing.

The first, or preaxial, digit of the forelimb, corresponding to the hallux in the hind limb; the thumb. In birds, the pollex is the joint which bears the bastard wing.

the thick short innermost digit of the forelimb