Courteous language: polite expressions used to show respect; in this context, often refers to humble/courteous forms where the action or object is not directed toward the listener or a third party.
取引先には丁重語で対応し、失礼がないようにした。
We used courteous language with the client to avoid any rudeness.
年配の方には丁重語で話すことが多い。
I often speak with courteous language to elderly people.
辞書で丁重語の具体例を調べた。
I looked up concrete examples of courteous language in the dictionary.