Is there someone who you're close to who you're concerned may suffer from clinical depression? If so you must understand the condition better so that you can see if that's the problem they are dealing with. The definition of clinical depression is feeling extremely sad, downhearted, and miserable to such a degree that it interferes with the person's ability to function normally in their day-to-day life. Its somewhat different than feeling low all the time, which can be depression, but since it doesn't interfere with daily activities to the point of making it impossible to perform them its called depression or being depressed. Sometimes this feeling makes a person show a lack of ambition or seem to be down for no obvious reason. Still it's different than being diagnosed with clinical depression.