Suppose I want to refer to a very knowleageable person in a light-hearted, informal, yet not direspectful manner. For example,

This is a tricky question that requires insight and a historical background of English. I suggest you to consult the {very knowledgeable persons} in English Language Learners Stack, who will likely provide good answers.

Looking for "knowledgeable" in dictionaries, I have found "versed" and "lettered", but both sound too formal. Do you know any alternative?

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    Guru (definition 2)? Jan 4, 2021 at 12:19
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  • @FumbleFingersReinstateMonica Nice one, there is guru in that link. This question is a bit more specific, though, so I'm not sure if it is as duplicate.
    – LoremIpsum
    Jan 4, 2021 at 14:20
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    The fact that you've included "light-hearted" in your request significantly widens things. For example, egg-heads, boffins, mavens, etc. would normally be considered "pejorative", so they wouldn't be suitable suggestions unless you either asked for terms with negative connotations or "humorous" (perhaps "facetious") terms. But this is essentially a "list" type question, which I might well have closevoted as Off Topic on those grounds alone, if it hadn't already been asked and answered here before. Jan 4, 2021 at 14:30
  • @FumbleFingersReinstateMonica - As a New Yorker, where Yiddish words tend to enter American English almost osmotically, I'd have to say that I've never heard "maven" used as even the mildest possible pejorative. Jan 6, 2021 at 12:28

9 Answers 9


It’s not uncommon to see the word “guru” used for this. While the ‘formal’ meaning of the word implies spiritualism (and principally in Indian [subcontinental] philosophies), using it informally for ‘subject matter expert’ is common enough to be the second definition of guru in the Oxford dictionary.

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    I think of a guru as more an expert than a smarty-pants.
    – EllieK
    Jan 4, 2021 at 14:04
  • This is a bit off from the linked second-definition: "An influential teacher or popular expert.". This definition of guru refers to someone who's popularly recognized as an expert to a lay-community -- it's not quite the same thing as being an actual expert. For example, Bill Nye the Science Guy would be a science-guru, but not a science-expert. By contrast, a PhD quantum-physicist working in a lab somewhere might be an expert, but not necessarily a guru. Then Einstein could've been both an expert and a guru.
    – Nat
    Jul 6, 2021 at 15:33
  • Because there's a division between "expert" and "guru", the term guru can sometimes be a tad sarcastic -- potentially implying that someone's perceived-expertise is a popular misconception rather than legitimate. Sometimes it's a euphemism for charlatan.
    – Nat
    Jul 6, 2021 at 15:37

Consider "maven"

ma·ven /ˈmāvən/

noun informal•North American

noun: maven; plural noun: mavens

an expert or connoisseur.
"fashion mavens"

Origin 1960s: Yiddish.

Definitions from Oxford Languages (google search)

For technical experts I use "wizard" as in "I thank the wizards at tex.stackexchange.com for help typesetting this book"

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    "Wizard" was the first thing that came to mind for me as well. I imagine different groups of people would have different preferences here. Jan 4, 2021 at 23:13

I think the term "wonk" would fit in this context.


a person preoccupied with arcane details or procedures in a specialized field
broadly : NERD

In your example, "I suggest you to consult the wonks in English Language Learners". In my opinion it doesn't come across as overly formal.

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    "Wonk" has a slight negative connotation for me that seems contrary to OP's desire
    – Cireo
    Jan 4, 2021 at 22:10
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    @Cireo interesting, I've never felt that way. 🤷‍♀️
    – Kirk Woll
    Jan 4, 2021 at 23:02
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    @KirkWoll: The negative connotation is in the definition, they're "preoccupied with arcane details", which implies they sometime miss the forest for the trees, leaving big problems unsolved because they're so hyper-focused on their own narrow area of expertise. It's not a strong negative connotation (when it comes to stuff like gov't policy, you need people that pay attention to the details, you just also want people with broader vision), but it's a negative connotation nonetheless. Jan 5, 2021 at 1:06
  • @Cireo: Innocent negative connotations are not uncommon in lighthearted conversation though.
    – Flater
    Jan 6, 2021 at 11:06
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    I can't recall hearing this term much except for the phrase "policy wonks".
    – Barmar
    Jan 6, 2021 at 16:29

Brainiac is often used for this. Although it originally was the name of a comic supervillain, when used to describe a person, it doesn't imply any evil or villainous behavior, but just a very intelligent or knowledgeable person.

It usually indicates either grudging respect or affectionate envy for someone who is very smart or knowledgeable. It's not really derogatory, though like any term it can be used sarcastically to mean the opposite.

"Gerald is such a brainiac, he got a perfect score on his calculus test and I just barely got a C."

There's even a line of snack products which use Brainiac in their trademark for snacks which supposedly improve brain development in children. Regardless of whether they actually work, the fact that the word is used to appeal to parents who want smart children shows that it's not derogatory.

Genius is also sometimes used for this in relation to a specific topic, as in "He's a genius at baseball stats."

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    Brainiac works for smart / knowledgeable in general, but just for the record, it doesn't work well if you want to limit the meaning to a specific subject matter. e.g. "Gerald is a calculus brainiac" doesn't sound good to my ear, and you certainly wouldn't say "Gerald is a brainiac at calculus". Comparing other answers, "calculus guru" or "calculus wizard" do work very well. That's not a problem with this answer, just a usage note to help future readers know what contexts they can use each one in. Jan 5, 2021 at 5:49
  • Also, "brainiac" has connotations of general intelligence / problem-solving / thinking skills, moreso than knowledge. Often you need knowledge to be able to apply intelligence to a problem, and clever people often will have such knowledge in some areas, but that's not the part "brainiac" focuses on. Jan 5, 2021 at 5:52
  • @PeterCordes In popular culture, extensive knowledge is generally taken as a sign of intelligence, even though it may not be.
    – barbecue
    Jan 5, 2021 at 14:09

These aren't particularly respectful but there are a few which haven't been mentioned yet.

  • "Smarty pants" - Usually if someone is highly willing to share their knowledge, to the point of being obnoxious.
  • "Boffin" - Someone who understands more than the speaker is interested in learning. Typically a scientist.
  • Isn't boffin rather specific to British English? I can't recall it ever seeing used (written or verbally) by someone who wasn't British.
    – Tonny
    Jan 6, 2021 at 14:41
  • HI @Tonny, I'm English.
    – AJFaraday
    Jan 6, 2021 at 14:43
  • "Boffin" is a good one. Neutral or slightly positive, unlike "smarty pants" which is negative. Jan 6, 2021 at 18:20
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    I love the word "boffin" but absolutely nobody here in the US knows what I'm talking about when I say it.
    – barbecue
    Jan 6, 2021 at 22:40

In my company, we have an actual position for these people - Subject Matter Expert (SME). In conversation, we refer to them as smees or a smee.

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    SME is a pretty common way to refer to certain types of experts in the workplace, and I think it’s an interesting contribution do it gets a + from me. I’m not sure if it is the best choice for this context though, because it’s not “light hearted”. It’s actually pretty formal.
    – ColleenV
    Jan 7, 2021 at 18:39

brain box

2 chiefly British : a very intelligent person
I was good at school; I was a total brain box. At a small town school, being brainy was not necessarily an asset.
— Karine Polwart, quoted in The (London) Times Educational Supplement, 15 Feb. 2013

Source: https://www.merriam-webster.com/dictionary/brainbox


A common informal but not too disrespectful term is "egg-head".

If the person is young, you may be able to go with "whizz-kid".

There is also the word "boffin" but that also has connotations of "scientist".

You may also be able to get away with "brain-box", although that is often used to mean "skull".

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    Agreed that it's not extremely disrespectful, but there is very definitely an air of derision in its usage. Jan 4, 2021 at 12:27
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    @JeffZeitlin In my experience, only from people who are intimidated by intelligence. There's a popular TV quiz my mother was keen on called "egg-heads" where the challengers had to try to beat the resident "egg-heads". Nobody ever did. Jan 4, 2021 at 12:29
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    I like boffin, but it should be noted that that is very much a Commonwealth usage, and is almost unknown in North America. Jan 4, 2021 at 12:33
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    @LoremIpsum It may be different on opposite sides of the Atlantic. Both Wikipedia and TFD are (I believe) American. Here in the UK there is not quite the same opprobrium towards intelligent people as that which seems to fester in American high-schools, for example, where physical and sporting prowess are lauded over academic achievement to a level that is considered unusual in other countries. Jan 4, 2021 at 12:36
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    @JohnP There's the thing. They are not really derogatory terms in the UK. Patronising and condescending at most, but not derogatory. Must be a cultural thing. A high intellect and respect for learning are not condemned as a fault in the UK. Jan 4, 2021 at 20:14

Be careful as these terms are often quite specific to an era and culture. Avoid these:

  • Brainiac - 1950's USA
  • Wonk - 2000+ bullshitter
  • Boffin - 1940s or 3rd person reference to some technical person
  • Maven - USA hacker culture

There are things you can say directly to someone's face as a term of respect. To be honest I'd not use a single word, as this attempts to pigeon-hole somebody who is way beyond that narrowness. Instead, spell out your appreciation, wonder at their knowledge and wisdom. One way is "How do you know so much." 'Encyclopedia' is a nice thing to say. Or invent something like "You explain better than a Wikipedia article." (Clever people like compliments just like the rest of us.)

If you are referring to somebody like a teacher or author indirectly, say to your friends, then use a word they'd understand (obvious really). Wizard perhaps. Guru. Something over the top: "The fount of all wisdom." "She wrote the manual!"

You could say "What you/she don't know about subject isn't worth knowing."

If you're just trying to direct people to an expert, use the word 'expert'.

  • I agree about using "expert."
    – Justin
    Jan 6, 2021 at 15:44
  • Hi, welcome to ELL! Thanks for the answer. While I agree with some of your suggestions and admonishments here, I thought your post was hard to read, which is probably why it was flagged by community members as "Not an answer". I don't know why you rolled back on an edit that helped reformat your post.
    – Eddie Kal
    Jan 7, 2021 at 20:28
  • Because the format and content were fine. Avoiding traps that make the person saying/writing them look out of touch is very important. Currency in popular idiom is essential.
    – Peter Fox
    Jan 8, 2021 at 20:19

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