Grammar Mistakes

Cannot or Can Not: Know the Difference!

When you say that you are unable to do something, do you say that you cannot or can not do that? Both these spellings are acceptable and can be found in formal writing, and yet their meaning is slightly different. Read on to figure out what’s this difference and to never confuse these two phrases again.

Cannot or Can Not: Understanding the Basics

Quick Tips:

“Cannot” and “can not” are both correct, but they are used in different contexts.

  • Use “cannot” as the default form to indicate that something is not possible or not allowed.
  • Use “can not” when emphasizing a choice not to do something or when part of a larger grammatical structure.
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Cannot or Can Not | Definition, Usage

Cannot:

  • Meaning: It is the more common and preferred form of negating “can.” It indicates that something is impossible or not allowed.
  • Use: “Cannot” is a single word and is typically used in most cases where you need to express inability or prohibition.
  • Examples:
    • “I cannot attend the meeting tomorrow.”
    • “You cannot park here.”
  • Explanation: “Cannot” is the standard, more frequent form, used to show that someone is unable to do something or something is not permitted.

Can Not:

  • Meaning: This form is used less often and typically when emphasizing the possibility of not doing something or when “not” is part of a separate construction.
  • Use: “Can not” is used when “can” and “not” need to be separated for emphasis or grammatical reasons, often in cases where the choice to not do something is being emphasized.
  • Examples:
    • “You can not attend the meeting if you don’t want to.” (Meaning: You have the option to not attend.)
    • “I can not only dance, but also sing.” (Here, “not only” is part of a phrase.)
  • Explanation: “Can not” is used when there is a reason to separate “can” and “not,” often for emphasis or as part of a larger grammatical construction.

Common Mistakes

Using “can not” instead of “cannot” for general inability:

  • Incorrect: “I can not finish my homework tonight.”
  • Correct: “I cannot finish my homework tonight.”
  • Explanation: In most cases, “cannot” is the standard and correct form.

Using “cannot” when “can not” is meant to show an option:

  • Incorrect: “You cannot go if you want to skip it.”
  • Correct: “You can not go if you want to skip it.”
  • Explanation: “Can not” emphasizes the option of not doing something, while “cannot” suggests it’s not possible or allowed.

When it comes to the usage of “cannot” and “can not,” there are other related words that can cause confusion. In this section, we’ll discuss some of these words and how they differ from “cannot” and “can not.”

Cannot vs. can’t

“Cannot” and “can’t” are often used interchangeably, but there is a subtle difference between the two. “Cannot” is the proper spelling of the word, while “can’t” is a contraction of “cannot.” In other words, “can’t” is simply a shorter version of “cannot.”

Both “cannot” and “can’t” mean the same thing: that something is impossible or not allowed. For example, “I cannot lift this heavy box” and “I can’t lift this heavy box” have the same meaning. However, “cannot” is more formal and is generally used in written English, while “can’t” is more informal and is often used in spoken English.

Can not vs. could not

“Can not” and “could not” are two different verb phrases that are often confused with each other. “Can not” is the negative form of “can,” while “could not” is the negative form of “could.”

“Can not” is used to express the inability to do something in the present or future, while “could not” is used to express the inability to do something in the past. For example, “I can not swim” means that I am currently unable to swim, while “I could not swim” means that I was unable to swim in the past.

It’s important to note that “can not” is not the same as “cannot.” “Cannot” is a single word that is used to express the same thing as “can not.”

Cannot vs. Can Not Examples

Examples of “Cannot” 

  • You cannot make a crab walk straight.
  • Time past cannot be called back again.
  • She cannot afford a new dress.
  • The athletes cannot compete in any athletic events while suspended.

Examples of “Can Not” 

  • Roads can not only ruin the countryside, but also divide communities.
  • This product can not only smooth throat, but also cure the common faucitis and stomatocace effectively.
  • The CIP system can not only clean the medicines, but also control the microorganism’s cleaning.
  • It can not only cure the disease, but also postpone caducity and strengthen the body.
  • Prompt action by local people can not only prevent ultimate demolition, but also save many thousands of pounds in repair costs.
  • I can not only grow begonias, but also identify them.

Quiz: “Cannot” vs. “Can Not”

Let’s test your knowledge on the usage of “cannot” and “can not”. Below are some sentences, and you need to decide whether “cannot” or “can not” is the correct word to use.

  1. I _____ wait to see the new movie.
  2. She _____ believe what she just heard.
  3. We _____ afford to buy a new car.
  4. They _____ decide which restaurant to go to.
  5. You _____ always get what you want.

Answers:

  1. cannot
  2. can not
  3. cannot
  4. can not
  5. can not
A2 Knowledge Check · 5 questions

Cannot or Can Not: Know the Difference! — Practice Quiz

1 / 5
Q1

Question 1: Which sentence uses "cannot" correctly?

Question 1 options
"She cannot afford a new dress" correctly uses "cannot" as a single word to express inability. The other sentences incorrectly use "cannot" where "can not" is needed (in "not only...but also" constructions) or misuse the word entirely.
Q2

Question 2: "Cannot" and "can not" mean exactly the same thing and can always be used interchangeably.

Question 2 options
This is false. While both are acceptable, their meanings are slightly different. "Cannot" expresses inability or prohibition, while "can not" is used to emphasize a choice not to do something or when "not" is part of a larger grammatical structure like "not only...but also."
Q3

Question 3: I ___ finish my homework tonight. (expressing general inability)

Question 3 options
When expressing general inability, "cannot" is the standard and correct form. "Can not" would only be appropriate when emphasizing a choice or when "not" is part of a separate construction.
Q4

Question 4: Match each sentence to the correct form it should use.

Question 4 options
You ___ park here. (not allowed)
You ___ attend if you don't want to. (your choice)
I ___ lift this heavy box. (unable)
It ___ only cure disease, but also strengthen the body.
can not (emphasizing choice)
can not (part of 'not only')
cannot (inability)
cannot (prohibition)

Select an item on the left, then tap its match on the right.

"Cannot" is used for inability or prohibition (parking, attending). "Can not" is used when "not" is part of a separate phrase like "not only...but also" or when emphasizing a choice not to do something.
Q5

Question 5: What is the relationship between "cannot" and "can't"?

Question 5 options
"Can't" is a contraction of "cannot." Both mean the same thing — that something is impossible or not allowed. However, "cannot" is more formal and typically used in written English, while "can't" is more informal and common in spoken English.

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