barb n.

also barb wire, "fencing wire with sharp edges or points," 1863, American English; see barb (n.) + wire (n.). Originally for the restraint of animals.

"one whose occupation is to shave the beard and cut and dress the hair," c. 1300, from Anglo-French barbour (attested as a surname from early 13c.), from Old French barbeor, barbieor (13c., Modern French barbier, which has a more restricted sense than the English word), from Vulgar Latin *barbatorem, from Latin barba "beard" (see barb (n.)).

Originally also regular practitioners of minor surgery, they were restricted to hair-cutting, blood-letting, and dentistry under Henry VIII. The barber's pole (1680s) is in imitation of the ribbon used to bind the arm of one who has been bled.

"repellent, unattractive," 1885, from French rébarbatif (14c.), from barbe "beard," from Latin barba (see barb (n.)). The usual theory is that it refers to the itchy, irritating quality of a beard.