This is the 4018th most frequent Japanese word.
トリュフ
"トリュフ" means "truffle," referring to either the edible fungus or the chocolate confection.
Here, 'トリュフ' is used to refer to the high-class culinary fungi often used in gourmet cooking.
トリュフは高価な食材です。
Truffles are expensive ingredients.
In this instance, 'トリュフ' is used to describe chocolates filled with a soft center typically known as truffles.
このチョコレートにはトリュフが入っています。
This chocolate contains truffles.
The usage of 'トリュフ' here pertains to the underground mushrooms grown in forested areas and sought after using trained animals.