Mastodawn

The German word "verbessern" means "to make better".

The word "verschlimmern" means "to worsen".

The word "verschlimmbessern" means "to make worse by trying to make better".

Anyone ever trying to fix something and fucking it up badly will feel this one.

Enjoy our language!

@jensclasen Wiktionary suggests "disimprove" as an English word that may be losing its older meaning and taking on this meaning instead. :-)