Bolas (from Spanish bola, "ball", also known as boleadoras, or Inca ayllo) are a throwing weapon superficially similar to the surujin, made of weights on the ends of interconnected cords, designed to capture animals by entangling their legs. They are most famously used by the South American gauchos, but have been found in excavations of Pre-Columbian settlements, especially in Patagonia, where indigenous peoples used them to catch guanaco and ñandú. They have also been found, as a Stone Age lithic tool, in North America at the Calico Early Man Site.

Gauchos use boleadoras to capture running cattle or game. Depending on the exact design, the thrower grasps the boleadora by one of the weights or by the nexus of the cords. He gives the balls momentum by swinging them and then releases the boleadora. The weapon is usually used to entangle the animal's legs, but when thrown with enough force might even inflict damage (e.g., breaking a bone).

There is no uniform design; most bolas have two or three balls, but there are versions of up to eight or nine. Some bolas have balls of equal weight, others vary the knot and cord. Gauchos use bolas made of braided leather cords with wooden balls or small leather sacks full of stones at the ends of the cords.