There are French phrases that have made it into the English vernacular. One that might be the most associated with fine-dining is "amuse-bouche" (pronounced "ahmooz-boosh").
An amuse-bouche is a complimentary small bite served at the start of a meal, often presented as "a gift from the chef." It serves a purpose and is different from an appetizer.
An amuse-bouche is a tiny dish that serves as a chef's first impression for diners. It packs flavors and is meant to awaken the palate in preparation for the meal to come.
You also don't get to choose your amuse-bouche like you do with an appetizer. Rather, the chef dictates what it is, and usually, every guest is served the same one.