Mismatch: word class: noun/adjective
Both nouns and attribute adjectives decline for case-number, but adjectives show a further sensitivity to the preceding modifier, as illustrated by the masculine forms of gut 'good':
| singuar | |||
| 'good colleage' | 'a good colleage' | 'the good colleague' | |
| NOM | guter Kollege | ein guter Kollege | der gute Kollege |
| ACC | guten Kollegen | einen guten Kollegen | den guten Kollegen |
| GEN | gutes Kollegen | eines guten Kollegen | des guten Kollegen |
| DAT | gutem Kollegen | dem guten Kollegen |
einem guten Kollegen |
| plural | |||
| 'good ones' | 'the good ones' | ||
| NOM/ACC | gute Kollegen | die guten Kollegen | |
| GEN | guter Kollegen | der guten Kollegen | |
| DAT | guten Kollegen | den guten Kollegen | |
Adjectives may be regularly converted to nouns without any change in form or declensional behaviour, e.g. Guter 'good one (M)', Gute 'good one (F)', Gutes 'good one (N)'.
There is one noun, Beamter 'civil servant', which declines like an adjective (i.e. as gut above), but is not synchronically derived by conversion from an adjective. Further, it exists only as a masculine; the corresponding feminine, Beamtin, is morphologically a noun. (Etymologically, it derives from Beamteter, a substantivization of the past participle beamtet, which in turn presupposes an unattested verb beamten; Grimm and Grimm 2004).
References
Grimm, Jacob and Willhelm Grimm. 2004. Deutsches Wörterbuch (Digital edition). Frankfurt am Main : Zweitausendeins.