late 14c., "barb of an arrow," from Old French barbe "beard, beard-like appendage" (11c.), from Latin barba "beard," from Proto-Italic *farfa- "beard," which might be from a common PIE root *bhardhā- "beard" (source also of Old Church Slavonic brada, Russia boroda, Lithuanian barzda, Old Prussian bordus), but according to De Vaan the vowel "rather points to a non-IE borrowing into the European languages."
late 15c., "to clip, mow" (a sense now archaic or obsolete); see barb (n.). Meaning "to fit or furnish with barbs" is from 1610s. Related: Barbed; barbing.