January 26, 2019:
People think "depression" means "sadness", whether they're talking about you or themselves. They'll say, "I'm not depressed," although they're living on comfort food, not exercising, are socially isolated, not changing the sheets, not taking out the garbage. Because they don't feel sad about any of this. They just can't face it, and because they have a misconception of the meaning of "depression" they fail to seek appropriate treatment.
Or they'll apply it to you, suggesting helpfully that "When I'm depressed I xyz," where "xyz" is some well-meaning triviality about hitting the gym or listening to Katy Perry. Because they're incorrectly assimilating "depression" to "sadness" and fundamentally they have no clue.
The worst is when they say "just". "Just smile, you'll feel better!" "Just get out in the sun, you'll feel better!" "Just listen to Katy Perry, you'll feel better!" Where you're thinking, Just fuck off, then I'll feel better. And you increase your self-isolation because it's too much effort to explain reality.
I've known so many people who could have had better lives if they'd treated their depression. The first step is the same as for addiction: acknowledging you've got it. That oftentimes starts with comprehending what it is.