Noun adjunct
In grammar, a noun adjunct, attributive noun, qualifying noun, noun (pre)modifier, or apposite noun is an optional noun that modifies another noun; functioning similarly to an adjective, it is, more specifically, a noun functioning as a pre-modifier in a noun phrase. For example, in the phrase "chicken soup" the noun adjunct "chicken" modifies the noun "soup". It is irrelevant whether the resulting compound noun is spelled in one or two parts. "Field" is a noun adjunct in both "field player" and "fieldhouse".