Aliquis is typically a pronoun, but can it also function as an adjective like aliqui? For example, aliqui homo currit versus aliquis homo currit.
I disagree with LaFeeVerte, and would like to posit that aliquis can function as an adjective. A quote from one of my favorite sources, Bennett's Latin Grammar:
- Aliquis may be used adjectively, and (occasionally) aliquī substantively.
Unfortunately, no examples are provided to show its adjectival use, but the fact that it can be used as an adjective makes sense based upon dictionary definitions elsewhere, such as this one from Lewis Elementary, which does provide a quote from Terence as an example:
II.II. adj. (cf. aliqui): nos quibus est alicunde aliquis obiectus labos, T.: ut aliquis metus adiunctis sit ad gratiam.
As Cataline mentions, there is a separate adjective (aliqui, aliqua, aliquod that means "some, any" that would serve the same purpose as the pronoun aliquis; however, aliquis can still serve as an adjective.
Generally, the answer is no. The adjective 'aliqui, aliquae, aliquod' should be used instead.
That being said, however, Virgil (Aeneid, book II, line 48) seems to use 'aliquis' as an adjective, saying 'aut aliquis latet error'. Here both 'aliquis' and 'error' are in the nominative, which suggests that you can use 'aliquis' as an adjective. But perhaps 'error' should be translated predicatively, as in 'something lies hidden as a trap' instead of 'some trap lies hidden'. So you probably shouldn't use it as an adjective, but you might not be wrong.