Is the word theater a common noun?

The word "theater" can be both a common noun and a proper noun, depending on its context.

Common noun:

* When referring to the general concept of a building or space used for theatrical performances, "theater" is a common noun.

* Example: "I love going to the theater to see plays."

Proper noun:

* When referring to a specific theater, "theater" becomes a proper noun.

* Example: "The Apollo Theater in Harlem is a historic landmark."

It's important to pay attention to the context to determine whether "theater" is functioning as a common or proper noun.