Depression may refer to:

• Clinical depression, a medically-defined state of mind identified by clusters of symptoms such as markedly-decreased motivation, interest, libido, activity, sense of pleasure, ability to sleep, etc. Crucially, unlike a transitory depressive mood, it is also concomitant with sustained changes in the production and absorption of neurotransmitters in the brain.
• Depression (mood), an everyday term for a sad or low mood or the loss of pleasure, but not clustered with other symptoms of clinical depression or a sustained change in brain chemistry.
• Depression (geology), a sunken or depressed geological formation.
• Depression (economics), used to describe a longer-lasting and more severe economic downturn than recession
• Depression (meteorology), an area of low atmospheric pressure associated with cyclones and weather fronts