How do you define a troll?

When I first heard the term, it was quite specific: someone who posts and debates online for the sole purpose of stirring up emotions, primarily anger. Later, it was used - at least here in Sweden - by media and others who want to influence the general discourse, with the meaning "someone spreading disinformation and misinformation", before those words were common. Sometimes (of course heavily overlapping with the latter) it's used to mean someone with a different opinion than the person saying "troll".

IMO trolling is the original definition, and thereby an active thing - you aren't trolling if you don't know you are trolling. Sometimes it's obvious when someone is trolling, sometimes it's not. I have been accused of trolling when I definitely weren't. It's possible I've accused non-trolls of trolling, I can't know that. I have seen countless of seemingly trolling posts by high-profile Nostriches, though they get likes and zaps by many others, including high-profile ones, leading me to believe they are ether collectively deluded, or they have such different thoughts than me that I could never see their point of view and they could never see mine, and in either case thereby aren't trolling.