Lethargy is a noun that refers to a state of extreme tiredness or lack of energy. It is characterized by a feeling of sluggishness, drowsiness, and a general lack of motivation or enthusiasm.

Interesting fact: The word “lethargy” originated from the Greek word “lethargia,” which means “forgetfulness” or “negligence.” In ancient times, lethargy was believed to be caused by an imbalance of bodily fluids, particularly an excess of phlegm. It was considered a medical condition and was often associated with melancholy or depression.