Q: I’m a medical student with a linguistic question. There are a lot of references to food in pathology: “nutmeg liver,” “berry aneurysm,” “orange peel ulcer,” “maple syrup urine,” etc. What part of speech are these food terms?
A: In a phrase like “berry aneurism,” the noun “aneurism” is being modified by an adjective: “berry.” In this case, the adjective is in fact a noun (“berry”) used adjectivally.
This is quite common. Take these examples: “bird brain,” “flower child,” “stone wall,” “car salesman,” “dog fight.” When a noun performs the function of an adjective, it’s sometimes called an attributive noun.
Any adjective (whether or not it’s also a noun) performs a similar function – it casts its own attributes onto the word it modifies.
So in the noun phrase “pink socks,” which is a more typical adjective-noun combination, the adjective lends its attributes (pinkness, mostly) to the socks.
And in the noun phrase “berry aneurism,” the noun “berry,” functioning as an adjective, lends its attributes (the characteristic size, shape, consistency, etc., of a berry) to the aneurism.
To sum up, the food terms in the phrases you mention are all attributive nouns – that is, nouns functioning as adjectives.
In case you’re interested, we recently answered another question that involved an attributive noun: a doctor wondered whether he should be called a “retina surgeon” or a “retinal surgeon.”