Is the word outside a common noun?

Yes, "outside" can be a common noun, but it is more often used as a preposition.

Here's why:

* Common noun: A common noun refers to a general person, place, or thing (e.g., dog, city, chair). "Outside" can be used as a common noun when it refers to the area or space that is not inside something.

* Example: "The outside of the building was covered in ivy."

* Preposition: A preposition shows the relationship between a noun or pronoun and another word in the sentence. "Outside" is commonly used as a preposition to indicate location.

* Example: "The dog is playing outside."

So, whether "outside" is a common noun or a preposition depends on how it is used in the sentence.