triphalangia

tri·pha·lan·gi·a

(trī'fă-lan'jē-ă), Malformation in which three phalanges are present in the thumb or great toe. [tri- + phalanx]

triphalangia

(trī″fă-lăn′jē-ă) [″ + phalanx, closely knit row] A deformity marked by the presence of three phalanges in a thumb or great toe.