The word depression can mean:

• A decrease of functional activity in behavior patterns
• The everyday term for a sad mood, see depression (mood)
• The medical condition clinical depression, which includes decreased interest in pleasurable activities
• A sunken or depressed geological formation, see depression (geology)
• An economic depression, is a more severe downturn than a recession
• The Great Depression, a particular instance of an economic recession
• A condition in meteorology associated with cyclones and weather fronts