Can “nuisance” be an adjective?

Question

According to Wiktionary there is a noun nuisance tax. Does this suggest nuisance can be an adjective? Is it?

Answer 1

What you have there is a noun adjunct.

In grammar, a noun adjunct, or attributive noun, or noun premodifier is a noun that modifies another noun, and is optional—meaning that it can be removed without changing the grammar of the sentence; it is a noun functioning as an adjective.

Answer 2

Nuisance is not an adjective in the strictest sense. Nuisance tax is what is known as a noun compound, and the first word in that phrase is known by a variety of names. See this question that talks about the variety of names (one is noun adjective, interestingly).

Other common noun compound examples are space shuttle and computer programming.

Answer 3

No it doesn't. Unfortunately, though this is a slightly unusual usage of "tax".

Normally, an X tax is a tax on X; income tax is a tax on your income, sales tax is a tax on the sale being made, window tax was a tax on the number of windows your house had, and so on. In all of these cases, X is of necessity a noun.

I hadn't come across the term nuisance tax before and Etymonline doesn't list it, but the definition you link to suggests that it derives from the tax being a nuisance itself. Despite the change in meaning, this is basically the same grammatical form as all the other taxes.