In a sense it is functioning as an adjective, but only in the same sense that “car” in “car door” is functioning as an adjective. We don’t call “car” a true adjective; instead it is an attributive noun. I believe that “swimming” in “swimming pool” is the same.
grammar.about.com/od/ab/g/Attributive-Noun.htm
[color=blue]Not surpringly, a lot of terminology gets tossed around, but I stand by what I have been taught about present particles. They function as adjectives. And this is supported by the link on attributive nouns.
There is a basic difference between a swimming fish, or a man swimming, and a swimming pool. In the first two the participle is adjectival. In the last case it is fundamentally a noun, though it modfies another noun somewhat in the manner of an adjective.
Well, you’re right about one thing, at least. It’s not ‘somewhat’.
The function of the present participle to show continuing action. That is not the case here.
As Dozy stated, it’s a noun.
I guess if you looked at the link, you didn’t notice that it was clearly stated the entire term ‘swimming pool’ is a noun. Of course the link has no bearing on what a present participle is - because there is no present participle in the phrase.
These have no bearing on what a present participle is too:
[color=blue]That’s the function of a continuous-tense verb. Unfortunately there is a some tendency to call all -ing verb forms that are not gerunds present participles. But of course, that lumps continuous tense verbs and present particples together, even though they have distinctly different functions.
If you want to delete the word “somewhat” then it’s no big deal. The main thing is that it is basically a noun, and that there is a basic difference between “swimming” in “swimming pool” and “swimming” in “man swimming”.
A man swimming (or a swimming man) is a man who is swimming. A swimming pool is not a pool that is swimming. Instead, “swimming” is the type of activity that is carried out there. “swimming pool” is analogous to “football pitch” or “golf course”. “football” and “golf” are also attributive nouns there.
Towards the bottom of the second column. “… is defining as used in this phrase a gerund (an -ing form of a verb used as a noun, as in swimming pool) or a participle (an -ing form of a verb used as an adjective, as in swimming children)?”