'barbule' originates from New Latin, specifically the word 'barbula', where 'barba' meant 'beard'.

'barbule' came into English from New Latin 'barbula' (a diminutive of Latin 'barba') and was adopted in the specialized sense referring to small beard-like structures on feathers.

Initially it meant 'little beard' (a diminutive of 'beard'), but over time it evolved into the specific anatomical meaning 'a small filament on a feather'.