ˈ ̷ ̷ˌ ̷ ̷ noun
1. : a filarial worm ( Dirofilaria immitis ) that is especially common in warm regions, lives as an adult in the right heart of dogs and some other carnivores, and discharges active larvae into the circulating blood whence they may be picked up by mosquitoes and transmitted to other hosts
2. : infestation with or disease caused by the heartworm resulting typically in gasping, coughing, and nervous disorder and when severe commonly leading to death