@Adam Going through the examples again, it is now making sense to me. In short, I think, use quis and quid for questions, use quī and quod for adjectival use, including relative clauses. Does that sound correct?
@CannedMan Simpler: use qui/quod for everything, except substantive interrogative pronouns. (Using quis for adjectival interrogatives is possible but uncommon.)
Note also that interrogative pronouns can be used in direct and indirect questions.
@cmw The Finnish word for a noun is "substantiivi". It's a noun, not an adjective. It took me a while to learn to use the English word "noun", and many Finns seem to have the same struggle. Many Finns without linguistic education say "substantive" instead of "noun", as they're entirely unfamiliar with the word.
The Norwegian word for noun is ‘substantiv’. I find that most Norwegians who have acceptable English, do know that the English term is ‘noun’, but amongst those whose English is poor, I would expect them to say ‘substantive’ (maybe even stressing the first syllable, as per the Norwegian word).
@Adam I'm familiar with this in verbs (like prodúce versus próduce), but not with adjectives. I'd be curious to see if adjectives do the same.
My natural inclination, which I've defeated, was to use the noun 'substantive' and the corresponding adjective 'substantival' (as 'adjective' and 'adjectival').
@Adam But 'substance' has it on the first. I'm not sure if that makes a good example, though.
