1. A state of feeling sad or a serious medical condition in which a person feels hopeless, and unimportant and is often unable to live in a normal way: Maja has been undergoing treatment for severe depression for quite awhile now.

After losing both parents in a car accident, Linda not only felt grievous but also very distressed and disheartened and found out from her doctor that she was suffering from a depression.

In psychiatry, a depression is not only a state of severe dejection, but it is also accompanied by a disorder of sleep, appetite, and an absence of energy.

2. A period of drastic decline in a national or international economy, characterized by decreasing business activity, falling prices, and unemployment: After several years of an economic boom, it looks as though some countries may now be heading for a financial depression.

Shirley was in a state of depression when her bank informed her of the small interest rate in her accounts because of the current financial conditions.

Starting with 1929 and into the subsequent years, many countries were hit by the "Great Depression", a massive plunge of finances and a decrease in businesses and industries.

3. An area that is lower than the rest of its surface: The depressions, or sunken places, in the street where Joan lives, provide places for pools of water after a rain.
4. Low air pressure in an area that is usually accompanied by misty and humid weather can cause tornadoes and hurricanes: A depression in weather can become a hurricane which begins with very bad weather and is known as a tropical depression.