What does the word “depression” mean?

When I was reading the article if Black man want to heal racism’s wounds, we can’t pretend to be strong all the time by Mychal Denzel Smith , I came across a familiar world people would always talk about so I really wanted to see how the professionals would address this word. According to Webster’s Dictionary the word means “a mood disorder marked especially by sadness, inactivity, difficulty in thinking and concentration, a significant increase or decrease in appetite and time spent sleeping, feelings of dejection and hopelessness, and sometimes suicidal tendencies”, this is really upsetting to know that people have to go through this yet I think some don’t know what depression truly means until they experience it, that’s depressing.