- Was ist das Präteritum von "darben"? -- verbs
- Grammatisch oder grammatikalisch? -- adjectives
- Eifersucht vs. Neid -- nouns
I believe that this usage is not useful. The purpose of tags is to make it easier to search questions, and I can't imagine anyone wanting to browse through all questions on specific nouns.
These tags have a better use, which is to mark general discussions on those lexical classes. Some good examples are:
- What is the origin of the rules about the capitalization of the first letter of each noun? -- nouns
- Verb inversion with adverbs used at the beginning -- verbs
I suggest that we do not use these tags for marking questions on specific words, but keep marking general discussions.