> Sorry? Apple is an adjective?

For purposes of a trademark, actually, yes. From Apple's own site [1], "Trademarks are adjectives, and should not be made into verbs or made plural or possessive." In addition, Apple specifies a list of suggested generic terms for each trademark. Under Guidelines for Using Apple Trademarks and Copyrights, some concrete examples are given [2]: "Correct: I bought two Macintosh computers." but "Not Correct: I bought two Macintoshes."

[1] https://www.apple.com/legal/intellectual-property/trademark/...

[2] https://www.apple.com/legal/intellectual-property/guidelines...

This is incorrect in multiple ways.

- Apple says this because it doesn't want its trademarks to become common words ineligible for trademark protection (like what happened to xerox and kleenex). But it can't stop people from referring to things however they please; this is nothing more than a statement of how Apple wishes the world would work.

- If I say "I bought two Apple computers", Apple is still a noun, not an adjective.

> But it can't stop people from referring to things however they please

Even if they send C&D notes over improper usage?

Yes, if you post "I bought two Macintoshes today" to your blog or write it in a commercial article or anything of the kind, Apple has no authority to prevent that (and a trademark likewise does not apply to such behavior). Their only authority is to stop you from using their mark on your unaffiliated products.