From prose + -y.

• (British) IPA: /ˈpɹəʊzi/

prosy (comparative prosier, superlative prosiest)

1. (of speech or writing) Unpoetic; dull and unimaginative.
2. (of a person) Behaving in a dull way; boring, tedious.
   • 1913, Arthur Conan Doyle, “(please specify the page)”, in The Poison Belt […], London; New York, N.Y.: Hodder and Stoughton, →OCLC ↗:

     "Well, well, we all get a bit prosy sometimes," said Lord John.

   • 1946, Bertrand Russell, History of Western Philosophy, I.19:

     I cannot imagine his pupil regarding him as anything but a prosy old pedant, set over him by his father to keep him out of mischief.

• prose

• German: nüchtern