Source : Webster's Revised Unabridged Dictionary (1913)

Zygodactylic \Zyg`o*dac"ty*lic\, Zygodactylous
\Zyg`o*dac"tyl*ous\ (?; 277), a. [Gr. ? a yoke, pair + ? finger,
   toe: cf. F. zygodactyle.] (Zo["o]l.)
   Yoke-footed; having the toes disposed in pairs; -- applied to
   birds which have two toes before and two behind, as the
   parrot, cuckoo, woodpecker, etc.