Obtuse Meaning: Here’s What It Means and How to Use It?

Wondering what obtuse means? If so, you’re in the right place! Read on to discover everything you need to know about the term obtuse.

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If you paid any attention to your grade school teacher, you might already know that an obtuse angle is between 90 degrees and 180 degrees, but what you may not have known is that the word “obtuse” has another meaning.

I this article, we’ll tell you all about it. Read on to discover everything you need to know about the term obtuse.

What Is the Definition of Obtuse?

When looking to understand new words, it can be helpful to review a number of definitions from a multitude of sources as opposed to just one. To begin our journey in understanding obtuse, we’ve put together a list of definitions for you to review, provided by three reputable sources:

  • According to the Macmillan Dictionary, someone who is obtuse doesn’t understand explanations or situations quickly. 
  • The Oxford English Dictionary defines obtuse as annoyingly insensitive or slow to understand. When used as an adjective, obtuse can also mean “blunt” or “rounded.”  
  • The Collins Dictionary says someone who is obtuse has difficulty understanding things or makes no effort to understand them. This dictionary also says the word obtuse can refer to an angle that is between 90° and 180°. 

After reviewing the definitions listed above, we can conclude that obtuse means not quick or alert in perception, feeling, or intellect — AKA, not sensitive or observant. 

In other words, when a person is obtuse, they are likely not the sharpest tool in the shed. That said, obtuse isn’t just for dull people but also dull angles. When used in geometry, an obtuse angle is one that is between 90 and 180 degrees.  

What Is the Origin of Obtuse?

The word obtuse derives from Middle French obtus (meaning narrow-minded, boring, dull, or lifeless) and the Latin obtūsus (meaning blunt or dull). This is the past participle of obtundere, from obtundō (meaning to strike at or upon, beat, blunt, or dull), which comes from ob (meaning upon) and tundere (meaning to strike). 

What Are Synonyms and Antonyms of Obtuse?

To further your understanding of obtuse, let’s take a look at a few synonyms and antonyms. Synonyms are words or phrases that have exactly the same or nearly the same meaning as another word. Antonyms, on the other hand, are words or phrases that have different meanings. 

Synonyms of obtuse:

  • Dull
  • Stupid
  • Slow-witted
  • Unintelligent
  • Witless
  • Dork
  • Half-baked
  • Doltish
  • Lumpish
  • Halfwitted
  • Slow 
  • Dopey
  • Brainless
  • Thickheaded
  • Dim
  • Baka
  • Abstruse 
  • Simple
  • Dense
  • Idiot
  • Fool
  • Dumb
  • Stolid
  • Uninformed
  • Slow on the uptake

Antonyms of obtuse:

  • Quick
  • Bright
  • Sharp
  • Smart
  • Clever
  • Ingenius
  • Astute
  • Quickness
  • Shrewd
  • Acute
  • Cutting
  • Edged
  • Edgy
  • Pointed
  • Sharpened
  • Whetted
  • Resourceful
  • Scholarly
  • Savvy
  • Wise

Examples of Obtuse in a Sentence

Now that you understand what obtuse means and we’ve covered a few synonyms and antonyms, it’s time to put what you’ve learned into practice. Quiz yourself to see how many complete sentences you can come up with using our word of the day, or check out our example sentences listed below:

If you ask me, Tom from HarperCollins Publishers is pretty obtuse!

We’re learning about acute and obtuse angles in math class.

Are you so obtuse that you’d give away your money to a fake charity?

My sister can be so obtuse sometimes when she talks about politics.

The teacher had us open up a thesaurus and dictionary to discover the etymology, definition, and synonyms of obtuse.

I am dealing with a dull, obtuse pain in my shoulder right now.

Did you know that the largest angle of an obtuse triangle is greater than 90 degrees, and the largest angle of an acute triangle is also greater than 90 degrees?

Although Henry may seem obtuse, he’s the smartest man I know.

Apparently, the obtuse angle was the only angle on the test that wasn’t a right angle.

Tonya was so obtuse that she didn’t even see that Bob was making sport of her.

He’s way too obtuse to take a hint.

There are a lot of obtuse puzzles in this game.

To be fair, not all of us think that your idea is obtuse.

Obtuse in Other Languages

Thinking about dusting off your suitcase to travel? In case you want to use the word obtuse abroad, here’s how to say it in a few other languages:

  • American English: obtuse /əbˈtus/
  • Brazilian Portuguese: obtuso 
  • Chinese: 迟钝的
  • European Spanish: obtuso 
  • French: obtus 
  • German: einfältig 
  • Italian: ottuso 
  • Japanese: 愚鈍な
  • Korean: 둔한
  • European Portuguese: obtuso 
  • Spanish: obtuso 


Like many words, obtuse has more than one meaning. When used in geometry, obtuse refers to an angle that’s between 90 and 180 degrees. In botany, it refers to leaf shapes and when used as an insult, obtuse can mean stupid. 

Whether used to describe someone who doesn’t really understand things or in regard to an angle, we hope this guide has provided you with all the information you need to understand obtuse. 

If you would like to discover more interesting terms to add some color to your vocabulary, we recommend checking out our website where you’ll find word lists, grammar tools, helpful tips, and more. 


  1. Obtuse (adjective) definition and synonyms | Macmillan Dictionary
  2. Obtuse: meaning, origin, translation | WordSense Dictionary
  3. Obtuse English Definition and Meaning | Lexico.com
  4. Obtuse definition and meaning | Collins English Dictionary