Sadness is a type of emotional distress that is accompanied or defined by emotions of disadvantage, loss, despair, sadness, helplessness, disappointment, and sorrow. When someone is unhappy, they may become quiet or sluggish and withdraw from others. Depression is an example of profound melancholy.... The best definition of sad I have ever heard is: being sad is when you feel sorry for yourself. There are many definitions of sad, but I think the best one is when you feel sorry for yourself.