sleeping sickness

US: /ˈslipɪŋ ˌsɪknɪs/

WordReference Random House Learner's Dictionary of American English © 2025

sleep•ing sick•ness /ˈslipɪŋ ˌsɪknɪs/  n. [uncountable]

1. Pathology an infectious, usually fatal disease of Africa, characterized by great fatigue and a wasting away of the body:
   Sleeping sickness is carried to the body through the tsetse fly.
2. Pathology a viral disease affecting the brain, characterized by sleepiness, muscular weakness, and difficulty in seeing.

WordReference Random House Unabridged Dictionary of American English © 2025

sleep′ing sick′ness, [Pathol.]

1. Pathology Also called African sleeping sickness, African trypanosomiasis. a generally fatal disease, common in parts of Africa, characterized by fever, wasting, and progressive lethargy: caused by a parasitic protozoan, Trypanosoma gambiense or T. rhodesiense, that is carried by a tsetse fly, Glossina palpalis.
2. Pathology Also called epidemic encephalitis, lethargic encephalitis. a viral disease affecting the brain, characterized by apathy, sleepiness, extreme muscular weakness, and impairment of vision.

Also,[Brit.,] sleepy sickness. 

• 1870–75

Collins Concise English Dictionary © HarperCollins Publishers::

sleeping sickness noun

1. Also called: African sleeping sickness an African disease caused by infection with protozoans of the genus Trypanosoma, characterized by fever, wasting, and sluggishness
2. Also called (esp formerly): sleepy sickness an epidemic viral form of encephalitis characterized by extreme drowsiness
   Technical name: encephalitis lethargica