common noun

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A noun, such as book or dog, that can be preceded by the definite article and that represents one or all of the members of a class.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A noun that can be preceded by an indefinite article, and denotes any member, or all members of a class; an ordinary noun such as "dog" or "city".

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a noun that denotes any or all members of a class