forefingernailEtymologyBlend of forefinger + fingernail. By surface analysis, forefinger + nail.forefingernail means the nail of the forefinger. Lexicurio rates it Sui generis — a strength score of 95 out of 100.nounThe nail of the forefinger.“Insert the right thumb and forefinger down into the center compartment of the twisted section and with the forefingernail uppermost grasp the center of the original bight (see arrow in the second diagram).”