>>1406616>depression is having good things in your life, and being completely unable to enjoy them because you're just miserable all the time for no good reason.This is what is known as a depressive episode or a depressive disorder; a mental illness.
There also exists congruent depression; it's not a disorder/illness/malfunction if you actually have a shit life. This latter definition is often ignored yet it's the more important one to keep in mind given that depression is at all time highs in the world, and believe it or not, a lot of our lives ARE shit despite our basic needs being met.