It CAN mean both at different times, but it CAN'T MEAN BOTH AT THE SAME TIME.
Which one did you, a "literate human being", assume it to mean in the "definition vs. usage" scenario? Did you read it to mean "prescriptive definition" which puts it opposite of "usage"; or did you read it to mean "descriptive definition" which puts it as equivalent to "usage". Which of the two did you think makes more sense opposite "usage", the opposed one or the identical one?
This is the same shit with "opinion" all over again. Words mean different things in different contexts. Just because a word can have two meanings (or more) doesn't mean IT ALWAYS HAS THOSE TWO MEANINGS AT THE SAME TIME or that you can use those two meanings the exact same way.