10 Best Words for Someone Who Thinks They Know Everything

It’s never nice when you have to deal with someone who thinks they know everything. They often think they’re smarter than you, which can be a really grating thing to deal with. This article will explore some of the best words you can use to refer to people like this.

Best Words for Someone Who Thinks They Know Everything

The preferred words are “know-it-all,” “smart aleck,” and “smarty pants.” All of these words work to show that someone thinks they know a lot sarcastically. They often want to act as if they know better than people, even when those people realize that they are just faking it.


“Know-it-all” is one of the most common words you can use to refer to someone who thinks they know everything. It’s a very common informal synonym that native speakers use negatively toward other people.

It’s an insulting word that works when you’re trying to show that you don’t care what someone knows. It’s often used when someone thinks they know more than you, even if they don’t have the information to prove it.

The definition of “know-it-all,” according to The Cambridge Dictionary, is “a person who thinks that they know much more than other people.”

  • Jessie is such a know-it-all. Nobody wants to hang out with us anymore because she always acts like she knows everything.
  • You don’t have to be such a know-it-all. You can just let other people say things without trying to tell them whether they’re right.
  • I’ve always thought of him as a bit of a know-it-all. I’ve never liked the way he’s spoken to his friends about stuff like that.

Smart Aleck

“Smart aleck” is an idiomatic expression you can use to refer to someone who thinks they know a lot. It works when you’re referring to someone who tries to appear smart, even when it’s clear that that isn’t the case with the other people around them.

The definition of “smart aleck,” according to The Cambridge Dictionary, is “someone who tries to appear smart or who answers questions in a funny way that annoys other people.”

  • He’s a smart aleck, and he’s very annoying about these kinds of things. I wouldn’t pay too much attention to what he has to say.
  • Don’t listen to that smart aleck. He’ll always try to say something that makes him sound cleverer than he actually is.
  • We all know she’s a smart aleck, so we should all tell her how we feel. We need to air our grievances before it’s too late.

Smarty Pants

“Smarty pants” is another colloquial phrase you can use to insult someone for thinking they’re intelligent. If they’ve come out with a flippant comment that makes them sound like they know better than you, it’s appropriate to say “smarty pants.”

“Smarty pants” is a very mild insult. It’s not directly supposed to upset the person you’re talking to, but it’s supposed to remind them that they don’t know everything.

The definition of “smarty pants,” according to The Cambridge Dictionary, is “someone who wants to appear to be clever.”

  • Stop being such a smarty pants! Nobody is impressed by your comments! We already know most of those things too.
  • I’m a smarty pants through and through. I won’t apologize for being smarter than everyone! I know I’m able to think better than most.
  • He’s a smarty pants, and many of us don’t want to see him again. He’s too much to bear. We just want him to leave.


“Self-righteous” is a decent synonym you can use in this context. It shows that someone thinks their knowledge or ideas are better than other people’s. They will refuse to give other people’s ideas the light of day because of how much better a self-righteous person thinks theirs are.

The definition of “self-righteous,” according to The Cambridge Dictionary, is “believing that your ideas and behavior are morally better than those of other people.”

  • Would you please stop being so self-righteous all the time? There’s so much more to life than trying to bring other people down.
  • You’re very self-righteous. What makes you think that you know any more about this type of stuff than I do?
  • I’m not saying you’re self-righteous, but you’re certainly close to that. I don’t really know how to talk to you anymore.


“Big-headed” relates to someone feeling more important or more intelligent than those around them. While they might not have a physically “big head,” the term is used to show that someone is very conceited and arrogant.

The definition of “big-headed,” according to The Cambridge Dictionary, is “thinking that you are more important or more intelligent than you really are.”

  • She’s big-headed in all the bad ways. I don’t think I’ve ever had a conversation with her that I’ve actually enjoyed.
  • Without sounding too big-headed, I do know what we need to do next. If you will all listen to me, I can get us out of this.
  • They’re both too big-headed for their own good. They’re only going to end up getting themselves into more trouble than it’s worth.


“Overconfident” works well when you know that someone is acting one way but they can’t back it up. If someone is acting like they are smarter than you, they might be overconfident because they’re lacking in other areas and feel like they need to make up for those deficits.

The definition of “overconfident,” according to The Cambridge Dictionary, is “having or showing too much confidence.”

  • You come across as overconfident, and that’s not a good thing. I think it’s quite clear that you’re not ready to take on the challenge.
  • You’re overconfident, and it’s going to be your downfall. You’re clearly not as smart as most of the other men around here.
  • Aren’t you being a little overconfident? Surely, there’s more to this than you realize. You need to open your eyes a little wider!


“Hubris” is a great noun you can use to relate to this context. You can use it when someone is too proud and acts in a way that makes them seem more important than other people. This pride can be closely linked to the superior knowledge that someone thinks they have.

The definition of “hubris,” according to The Cambridge Dictionary, is “a way of talking or behaving that is too proud.”

  • Your own hubris is going to be your downfall. I don’t know when it’s going to happen, but I can tell you that it’s going to be big.
  • I’m sure I’ve told you to bring your hubris back a little bit. It’s too intense, and people are going to start hating you for it.
  • It was his hubris that brought him down in the end. We all knew that he couldn’t handle being the least intelligent person in the room.


“Braggart” relates to someone who likes to boast about themselves. This can relate to any character trait, so it’s not uncommon to hear someone brag about how much smarter they are than other people.

The definition of “braggart,” according to The Cambridge Dictionary, is “someone who proudly talks a lot about himself or herself and his or her achievements or possessions.”

  • Sandra is a braggart. She’s always flailing her arms around, trying to tell everyone just how wonderfully smart she is. It’s annoying.
  • You’re a bit too much of a braggart for my liking. You need to take it down a notch or two. Nobody cares about what you know.
  • I know you’re a braggart for the sake of it. I’m not going to sink to your level, though. I’m going to rise above it.


“Blowhard” is a great way to show that someone thinks they’re important. They will often try to talk about themselves and the things they know. Other people usually zone them out or ignore them, but blowhards tend to have some of the loudest voices in a room.

The definition of “blowhard,” according to The Cambridge Dictionary, is “a person who likes to talk about how important they are.”

  • Oh, there goes the blowhard! He’s always talking about how superior he is. It’s about time that we put him in his place.
  • I get that you’re a blowhard by nature, but you really need to bring it down a peg or two. It’s getting too much to bear.
  • She’s a bit of a blowhard. I don’t think there’s anything we can do to bring her back to reality, though.


“Sanctimonious” is a bit more specific than some of the others. It relates to someone feeling superior in knowledge based on their moral or religious beliefs. If other people don’t agree with their beliefs, sanctimonious people consider them to be stupid.

The definition of “sanctimonious,” according to The Cambridge Dictionary, is “showing that you believe you are morally better, or more religious.”

  • You’re so sanctimonious. It’s no wonder that all of your friends have decided to stop talking to you. I can hardly listen to you.
  • Stop being sanctimonious. It’s not a good look, and you’re turning everyone away from you. Start being more inclusive.
  • I’m sanctimonious. I get that, and I’m really trying to work on it. I’ve been told it a few times before, to be honest.