Tsetse \Tset"se\, n. (Zo["o]l.) A venomous two-winged African fly (Glossina morsitans) whose bite is very poisonous, and even fatal, to horses and cattle, but harmless to men. It renders extensive districts in which it abounds uninhabitable during certain seasons of the year. [Written also tzetze, and tsetze.]

Source: Webster's Revised Unabridged Dictionary (1913)