/usr/share/opendict/dictionaries/plain/ is in dict-de-en 1.7-2ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/opendict/dictionaries/plain/english-german.dict.dz/
/usr/share/opendict/dictionaries/plain/english-german.dict.dz/conf/
/usr/share/opendict/dictionaries/plain/english-german.dict.dz/conf/config.xml
/usr/share/opendict/dictionaries/plain/english-german.dict.dz/file/
/usr/share/opendict/dictionaries/plain/english-german.dict.dz/file/english-german.dict.dz
/usr/share/opendict/dictionaries/plain/english-german.dict.dz/file/english-german.index
/usr/share/opendict/dictionaries/plain/german-english.dict.dz/
/usr/share/opendict/dictionaries/plain/german-english.dict.dz/conf/
/usr/share/opendict/dictionaries/plain/german-english.dict.dz/conf/config.xml
/usr/share/opendict/dictionaries/plain/german-english.dict.dz/file/
/usr/share/opendict/dictionaries/plain/german-english.dict.dz/file/german-english.dict.dz
/usr/share/opendict/dictionaries/plain/german-english.dict.dz/file/german-english.index