nursing coffee

東野圭吾の小説 "New Comer" を読んでいます。

'Did you notice how this place writes its name, Kissako, on the sign out front?' asked Kaga, nursing his coffee. 'With the ideograms for enjoy, tea, and go?'

"nursing his coffee" の状態が分かりません。辞書を見ます。
・Oxford English Dictionary: nurse something to hold a drink for a long time, drinking it slowly: He sat nursing his cup of coffee.
・Cambridge English Dictionary: to hold a drink for a long time without drinking it: Mark was sitting in the corner nursing an almost empty bottle of beer.

"nursing his coffee" の意味・用法はどの辞書でも最後の方に記載していますね。
・Vocabulary.com: A nurse is a trained healthcare worker who takes care of sick people. To nurse is to take care of, like if you nurse a baby bird back to health.
To become a nurse, you have to go to college and study subjects like anatomy and nutrition. Some nurses assist doctors and perform tasks like bathing patients, taking blood samples, or giving medication. When you use the word nurse as a verb, it means "care for," and also "breastfeed a baby." The Latin root, nutrire, means "to nourish." To nurse a drink is to drink it slowly, and to nurse an idea is to mull it over.