Coma vs. Comma: What’s The Difference?

Have you ever been confused by two words which are spelled nearly the same, but have different meanings? Coma and comma are two such words. Their meanings do not overlap, even though there is only one letter’s difference in their spellings.

One of these words refers to sentence punctuation. The other has multiple meanings, but none of them are related to grammar. Read on to find out which is which.

What is the Difference Between Coma and Comma?

In this article, I will compare coma vs. comma. I will use each word in a sentence to illustrate their proper uses. Plus, at the end, I will explain a useful trick to help you choose comma or coma in your writing.

When to Use Coma

Comma versus comaWhat does coma mean? Coma is a noun. It usually means a vegetative state of prolonged unconsciousness.

  • At the time of the accident, Ms. Gossiaux had taken a semester off to recover from cochlear-implant surgery. She awoke from a coma unable to see or hear. –The Wall Street Journal

Writers tend to use coma outside its medical context for any deep or extended period of sleep, as well.

For example,

  • Every Thanksgiving, the turkey puts my uncle Bob into a food coma.
  • Sheila survived the wreck, but she is in a coma.

A coma can also be a part of a comet, specifically, a cloud of gas and debris surrounding the nucleus. You can see in an example in the sentence below.

  • You can easily distinguish a comet from a star, due to the former’s coma giving it a hazy appearance through a telescope.

This usage is legitimate, but uncommon outside of technical astronomical contexts.

When to Use Comma

Definition of coma definition and definition of comma definitionWhat does comma mean? A comma is a mark of punctuation. I’ve used several in this article, and one in this sentence.

Commas are used to separate clauses, indicate short pauses, and to make lists of three or more items easier to read. They are an important tool in crafting sentence structure, but they can be distracting if you use too many.

Here are some examples of the word comma, in sentences which illustrate grammatically correct comma use.

  • The comma, the colon, the semicolon, and the dash are all used to separate phrases and clauses in sentences.
  • If you have more than one comma in a sentence that doesn’t contain a list, ask yourself if you should divide it into two or more sentences instead.
  • When my kids bring me an essay to proofread, they may well up in tears if I mention a missing comma. –The Washington Post

Trick to Remember the Difference

Define coma and define comma Here is a helpful trick to remember comma vs. coma in your writing.

  • Both comma and coma are nouns.
  • A comma is a mark of punctuation.
  • A coma can refer to a medical condition or a part of a comet.

It’s easy to remember when to use comma—comma and grammar share the letters mm. By using this trick, you will never have to wonder whether to use coma or comma again.


Is it coma or comma? Coma and comma are both nouns, but they have completely different meaning.

  • A coma is either a medical condition or a part of a celestial object.
  • Writers use commas to punctuate sentences.

Since comma and grammar both have a double m, you should have no trouble reserving comma for discussions of grammar and sentence structure.

If you find yourself unable to remember which word is which, you can always refer back to this article for a quick refresher.