No it is a noun
The adjective is 'marine'.
No. "Portuguese water dog" is a noun phrase. "Portuguese" is an adjective; "water" is a noun; they both are modifying "dog".
Yes, it is an adjective. It means pertaining to water, swimming, or the sea.
The word well is an adjective, for example well water or well wisher.
"cold" is an adjective, and "water" is a noun.
Hot
Water Skiing is only hyphenated when it serves as an adjective. Examples: Water skiing Water-skiing dock (Adjective) Water-skiing adventure )Adjective) This rule applies to any two, three, four or more stream of words. Example: I joined the Once-in -a-Lifetime-Crazy-Kids club.
Yes, fizzy is an adjective. The soda was very fizzy. The fizzy water had too much sodium in it.
Both. In the sentence "Are you still here?", it is an adverb; in the sentence "The water was quiet and still", it is an adjective.
it is by the water fountain
Examples of adjectives that are formed from a noun are:air (noun) - airy (adjective)artist (noun) - artistic (adjective)beauty (noun) - beautiful (adjective)blood (noun) - bloody (adjective)fish (noun) - fishy (adjective)hope (noun) - hopeful (adjective)length (noun) - lengthy (adjective)memory (noun) - memorable (adjective)politics (noun) - political (adjective)thought (noun) - thoughtful (adjective)use (noun) - useful (adjective)water (noun) - watery (adjective)
deaf (This answer is as simple as drinking water)