Discussion on answer by FumbleFingers: Wildcard character—noun or adjective?

@Lambie As with pronunciation matters, you should not blindly believe dictionaries for grammar matters. For one thing, that is simply not what they are good at. But for another they sometimes use outdated or simplified models for the sake of presenting a watered-down, shortened, and simplified version of reality to learners despite those reductions leading them completely out of step with the science of linguistics. So grammar and pronunciation in my first sentence and learners in this one are not "nouns used as adjectives" no matter what you might find some learners dictionary say.