Exhaustion is a feeling of extreme physical or mental tiredness. There are several synonyms for the word exhaustion, including weariness, fatigue, burnout, lethargy, enervation, depletion, and debilitation. Weariness is the feeling of being tired, used especially for a long period of time without rest. Fatigue refers to the inability to complete daily activities due to extreme tiredness, often caused by physical or mental stress. Burnout is a state of emotional and physical exhaustion caused by prolonged exposure to stress. Lethargy is a feeling of sluggishness, lack of energy, and motivation. Enervation is a gradual loss of energy or strength. Depletion refers to the feeling of being completely emptied or drained of energy. Debilitation refers to a state of weakness or reduced strength caused by exhaustion or illness.