What do you call a noun that precedes and describes another noun? [duplicate]

Question

Possible Duplicate:
What is the word that denotes the words preceding these nouns?

Would it still be a noun, an adjective, or something else?

Example:

A stone fortress

Answer 1

In most cases, I believe, the 'other things' are themselves going to be some kind of nouns, in that case:

Nouns can sometimes describe other nouns (such as a soccer ball). When they do this, they are called modifiers.

Quoted from and refer for more details: http://simple.wikipedia.org/wiki/Noun