/usr/include/mate-dict/gdict/ is in libmatedict-dev 1.12.0-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/mate-dict/gdict/gdict-client-context.h
/usr/include/mate-dict/gdict/gdict-context.h
/usr/include/mate-dict/gdict/gdict-database-chooser.h
/usr/include/mate-dict/gdict/gdict-defbox.h
/usr/include/mate-dict/gdict/gdict-enum-types.h
/usr/include/mate-dict/gdict/gdict-source-chooser.h
/usr/include/mate-dict/gdict/gdict-source-loader.h
/usr/include/mate-dict/gdict/gdict-source.h
/usr/include/mate-dict/gdict/gdict-speller.h
/usr/include/mate-dict/gdict/gdict-strategy-chooser.h
/usr/include/mate-dict/gdict/gdict-utils.h
/usr/include/mate-dict/gdict/gdict-version.h
/usr/include/mate-dict/gdict/gdict.h