Lethargy indicates a serious medical condition that requires immediate medical attention. It refers to an abnormal lack of alertness and spontaneous movement beyond weakness. True signs of lethargy include a lack of interaction with the environment, decreased eye contact and focus, and an inability to follow simple commands or respond to questions. While callers may use the term lethargy to describe less severe behaviors, any report of lethargy, listlessness, or excessive sleepiness requires clarification and exploration to diagnose potential underlying issues like meningitis or sepsis.