'barbule' originates from French, specifically the word 'barbule', ultimately from Latin 'barba' meaning 'beard' (with diminutive formation).

'barbule' comes via French 'barbule' (a diminutive of 'barbe') ultimately from Latin 'barba' ('beard'); the form was adopted into English in technical biological usage.

Initially related to the idea of a 'small beard' or tiny beard-like projection; over time it became the technical term for the minute beard-like branches on a feather (and by extension other small bristle-like projections).