Is commercial a noun

Yes, the Word commercial is a noun, a singular, common, abstract noun; a Word for a paid advertisement: The commercial for our new product is ready for distribution.

The Word commercial is also an adjective, a Word that describes a noun: The commercial bread is not as good as my homemade bread.

If by commercial you mean 'a commercial' then it is. If you mean 'commercial activity' then it is not. A rule of thumb, if you can put 'a' or 'the' in front of a Word, then it is a noun. If you cannot, then it is not a noun.