Nameerror name ‘x’ is not defined

In this article, we’ll show you how to fix Python nameerror name ‘x’ is not defined error message.

If you’re new to this error, it might be hard for you to resolve this error. Luckily, this article will explore the solutions to this error.

Aside from that, we’ll discuss details that will help you to understand this nameerror: name x is not defined error thoroughly.

What is “nameerror name ‘x’ is not defined”?

The nameerror name ‘x’ is not defined is an error message when you are trying to use a variable or a function named “x,” but “x” has not been defined or assigned a value.

Here are some scenario’s that you will encounter this error.

For example:

a = 5
b = 10
x = a + b + x
print(z)

Since we did not define the value of “x,” as a result, it will raise an error message.

NameError: name 'x' is not defined

To fix this error, you have to define the variable “x” before we try to use it in our expression.

a = 5
b = 10
x = 15
z = a + b + x
print(z)

Output:

30

Another example:

person = {
    'name': 'Caren',
    'age': 18,
    'address': 'Korea',
    'status': 'single',
}

print(Person)

If you try to run this code, the the results would an error because we have misspelled the variable’s name.

NameError: name 'Person' is not defined. Did you mean: 'person'?

To fix the error, we need to spell the variable’s name correctly.

person = {
    'name': 'Caren',
    'age': 18,
    'address': 'Korea',
    'status': 'single',
}

print(person)

Output:

{'name': 'Caren', 'age': 18, 'address': 'Korea', 'status': 'single'}

Why doe this error occur?

This error nameerror: name ‘x’ is not defined  can happen because of some reasons, such as:

👎If you misspelled the variable name.

👎 If you forgot to define the variable x.

👎 If the variable is out of scope.

👎 If you are using a variable that doesn’t exist.

👎 If you are using a variable or function before it is being declared.

How to fix “nameerror name ‘x’ is not defined”?

To fix the nameerror: name ‘x’ is not defined error in Python, ensure that the variable or function named x is defined before it is used.

Solution 1: Define the variable

When the variable x is not defined, you can define it by assigning a value to it.

Variable not defined:

❌ print(x)

Variable defined:

✅ x = 10
print(x)

Output:

x = 10
print(x)

Solution 2: Check Typos

Ensure that the variable name is spelled correctly everywhere it is used in the code.

For example:

❌ a = 20
print(a)
print(x) 

Solution 3: Import missing module

If x is a function or a class from a module that has not been imported, you can fix the error by importing the module.

✅ import math

x= math.sqrt(64)
print(x)

2.0

Solution 4: Verify the scope

Ensure that the variable x is defined in the same scope where it is being used. Variables defined inside a function or a loop are only accessible within that function or loop.

❌Variable out of scope:

def my_function():
    x = 100

my_function()
print(x)

✅ Variable in scope:

def my_function():
x = 100
print(x)

my_function()

Conclusion

In conclusion, the nameerror name ‘x’ is not defined is an error message when you are trying to use a variable or a function named “x,” but “x” has not been defined or assigned a value.

To fix the you have to ensure that the variable or function named x is defined before it is used.

This article already provides solutions for this error to help you fix the Python error message.

You could also check out other “nameerror” articles that may help you in the future if you encounter them.

• Nameerror: name plt is not defined
• Nameerror name np is not defined
• Nameerror name ‘raw_input’ is not defined

Hoping that this article helps you fix the error. Thank you for reading itsourcecoders 😊

Function-related NameError

NameError on a function usually means the function was not defined yet, the wrong name was used, or the function is in a different scope.

Common triggers

• Function name typo. caclulate() instead of calculate().
• Called before def. At module level.
• Function in wrong module. Imported from a different module than expected.
• Decorated function shadowed. Decorator returned wrong name.

Diagnostic pattern

# BAD — undefined function
def main():
    result = compute_total()   # NameError if compute_total not defined

main()

# GOOD — check spelling and scope
def compute_total():
    return 42

def main():
    result = compute_total()
    print(result)

main()

# For decorated functions, make sure functools.wraps is used
from functools import wraps

def my_decorator(fn):
    @wraps(fn)
    def wrapper(*args, **kwargs):
        return fn(*args, **kwargs)
    return wrapper

Best practices

• Use editor autocomplete. Prevents most typo NameError.
• Order definitions before calls at module level.
• Use type hints. Editor flags undefined names immediately.
• Use functools.wraps in decorators to preserve the original function name.

Caren Bautista

Technical Writer at PIES IT Solution

Responsible for crafting clear, well-structured, and beginner-friendly content across the platform. Handles the writing, proofreading, and editorial review of tutorials, guides, and documentation to ensure every article is accurate, readable, and easy to follow.

Expertise: Technical Writing · Content Creation · Documentation · Editorial Writing · JavaScript · TypeScript · Python · Python Errors · HTTP Errors · MS Excel
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