It’s fine to use generic words in trademarks, but generally not generic words from the domain the trademark is being registered in. So you can trademark ‘apple’ in the domain of computers, but not in the domain of fruit. And you can register ‘windows’ in the domain of operating systems but not in the domain of construction.

‘Bake-off’ is a generic baking term registered in the domain of baking, which is odd.

(Lots of operating system desktop environments have ‘windows’ as a concept but it wasn’t as commonly known at the time.)