The Wikipedia article Morphology says:
A further difference is that in word formation, the resultant word may differ from its source word's grammatical category whereas in the process of inflection the word never changes its grammatical category.
I can partly understand this statement and how "dishwasher" is different from both "dish" and "washer", but I couldn't understand how "the word never changes its category":
- I wash dish. (verb) / He breaks glass.
- A pile of washed dish (adjective) / some broken glass
"Washed" and "broken" are inflected forms of "wash" and "break", but they can be used as non-verb. This is clearly a different grammatical category.
I'm certainly misunderstanding either "inflection" or "grammatical category". What am I missing?