- any minute, flagellate protozoan of the genus Trypanosoma, parasitic in the blood or tissues of humans and other vertebrates, usually transmitted by insects, often causing serious diseases, as African sleeping sickness in humans, and many diseases in domestic animals.
- any parasitic flagellate protozoan of the genus Trypanosoma, which lives in the blood of vertebrates, is transmitted by certain insects, and causes sleeping sickness and certain other diseases
