In sushi dining, omakase is the Japanese word for the chef’s choice. It comes from a phrase meaning that the diner leaves the selection up to the chef rather than ordering every course from a menu.
An omakase meal commonly follows the chef’s judgment about seasonality, quality, and the order in which dishes should be served. At a sushi counter, that may mean a progression of appetizers, sashimi, nigiri, soup, and other preparations, with the exact menu changing from day to day.
Omakase is not simply another word for a fixed tasting menu. The chef generally chooses the dishes, and may adjust the sequence or ingredients according to the diner’s reactions, allergies, preferences, or appetite. Diners should still mention dietary restrictions before the meal begins.
Teishoku means a set meal, donburi refers to a rice-bowl dish, and kaiseki is a broader style of formal Japanese multi-course cuisine. Those terms therefore do not match the question’s specific dining instruction.