barb-wire

/B AA1 R B W AY0 ER0/
noun
  1. 1

    Twisted strands of steel wire, often coated with zinc, having barbs evenly spaced along them; used to construct agricultural and military fences.

Source: https://en.wiktionary.org/wiki/barb-wire, https://en.wiktionary.org/wiki/barbed%20wire