He is very careful in his choice of diction.

He is very careful in choosing words and phrases.

A determiner plays a role in specifying a noun.

At his funeral, I read a eulogy for him.

There are several words used as 働詞 in this ancient document.

The word 'hatarakikotoba' is used in this old document.

He wrote the original lyrics of the song.

The language used by courtesans during the Edo period, that's what 'Kuruwa Kotoba' is.

Shiba is my best friend.

In Japanese grammar, postpositions play an important role.