Lethargy
Part of speech: noun
Definition: A state of fatigue, sluggishness, lassitude and inactivity. A state of apathy with lack of emotion or interest. A state of comatose torpor (as found in sleeping sickness).
Example sentence: Hot, dry katabatic winds, like the south foehn in Europe, the sharav in the Middle East, and the Santa Ana of Southern California, are all believed to have a decided effect on human behavior and are associated with such health problems as migraines, depression, lethargy, and moodiness. Some scientists say that this is a myth.
Lassitude
Part of speech: noun
Definition: Lethargy or lack of energy; fatigue.Listlessness or languor.