'zygodactylous' originates from New Latin, specifically the word 'zygodactylus', where Greek 'zygon' meant 'yoke' and Greek 'daktulos' meant 'finger, toe', with the adjective-forming suffix '-ous'.

'zygodactylous' developed from New Latin 'zygodactylus' (formed from Greek elements 'zygon' + 'daktulos') and entered English through 19th-century zoological usage, becoming the modern adjective 'zygodactylous'.

Initially it literally meant 'yoked-toed' (toes united or paired like a yoke); over time it became the specialized anatomical term meaning 'having toes arranged two forward and two backward.'