> I think you're injecting your personal views into the definition,

I think I'm injecting what I know from getting a degree in political science and a two and half subsequent decades of experience paying attention to how political terminology is used by scholarly, journalistic, popular, and activist sources across the political spectrum into the definition.

> Here's the definition of the word taken from macOS's built-in dictionary

And that's a tolerably decent definition for a relatively compact general dictionary, but it misses a lot of nuance; outside of activist sources using it as a slur for their opponents, it is not used in nearly the local-politics-relevant way that left/right (especially qualified with a national label, like "American left") is.