It's a matter of grammar. Theatre can change it's vowel ending to become other words for example: theatrical, theatron, theatrics. Where as theater can only be used in that form. Therefore the study of Dramatics is Theatre because it encompasses all the elements of theatre and the vocabulary associated with it and theater only destines a place.
Kelly M. Thomas
Department of Theatre
Dr. Ralph H. Poteet High School
3300 Poteet Drive
Mesquite, Texas 75150
There's been a lot of nonsense written about "theater" and "theatre"-that one is for movies and the other is for plays; or that one refers to a building and the other to an art form; or that one spelling is lowbrow while the other is refined.
But these are merely variant spellings of the same noun.
The full quote is attached.So, take your pick if you are writing for American readers. The Revolutionary War goes on in our language. As an American, I use "theater" except for the spelling of names of theaters that have "theatre" in their names. But, as a playwright, I automatically default to British spelling when writing plays with an English setting. "Color" becomes "colour," etc. The real problem that I have as a writer is to figure out who my audience is!