OP

In forum discussions, OP often means "original poster." This acronym refers to the person who started a thread or discussion, by making the first post.

These days, you're most likely to encounter OP on Reddit, to reference the Redditor whose post began a thread. You can view each Reddit thread's OP by scrolling to its beginning and viewing the username listed next to Posted by.

You may also see OP used when one user links to another's content (often in a different forum). For example, if you click on a post titled "OP doesn't understand the water cycle," you can expect that post to link to another post, in which the original poster displays poor knowledge of the water cycle.

A quick reference to the operator of a game; similar to an admin or mod, where the person has a lot of power because they can control all of the aspects of the game; often utilized in games.

OP is often used online and when texting to describe someone who is "outta pocket," which is another way to say a person is "acting out of line" or "disreputable." It is typically used to refer to people cheating on their partner or just acting or saying crazy stuff.

Outta pocket was originally used to describe women who were disrespecting their pimp handlers. But it spread to a more general reference to people "acting up" when used in the rap community in the 2000s and social media in the 2010s.

You will most often see it on social sites, like Twitter, Instagram, and TikTok, when people talk about how someone is acting crazy in a way that is inconsiderate to themselves or others. However, people may also use it endearingly to describe people who do things that require courage and talent, even if they seem crazy.

Twitch viewers sometimes use OP to refer to a streamer's opponent. For example, a viewer might post "OP is making some really tight moves" in chat, to compliment an opponent's play.

However, because OP has several other, more popular meanings (which you can view on this page), this usage is fairly uncommon. If a Twitch viewer wants to abbreviate the word opponent, they're more likely to go with opp or oppo, so other viewers understand what they're saying.