The finger on the human hand that can be moved against each of the other fingers. Humans can grasp things and perform many delicate operations that would be impossible if they did not have opposable thumbs. Anciently, a captive was sometimes incapacitated for military service by having his thumbs and big toes cut off.​—Jg 1:6, 7.

The Hebrew word boʹhen is used to designate both the thumb and the big toe; the appendage that boʹhen has reference to in any given text is indicated by the accompanying expressions ‘of the hand’ and ‘of the foot.’ Whenever the thumb is mentioned in the Scriptures, the big toe is referred to in the same text.​—Ex 29:20; Le 14:14, 17, 25, 28.

During the installation of Aaron and his sons as priests, a ram was killed, and Moses put some of its blood on the lobe of Aaron’s right ear, the thumb of his right hand, and the big toe of his right foot. Then he did the same to each of Aaron’s sons. (Le 8:23, 24) The blood on the right thumb figuratively represented that they should carry out their priestly duties with the best of their ability.