Refers to a professional chef, especially the head chef in a restaurant kitchen. A common loanword from French.
from French
あのレストランのシェフはフランスで修行したそうです。
I heard the chef at that restaurant trained in France.
The chef at this restaurant is French.
シェフのおすすめ料理を注文した。
I ordered the chef's recommended dish.
He has served as the chef at that hotel for five years.
Borrowed from French 'chef', meaning chief or head, used in Japanese to refer to a professional chef, especially the head of a kitchen.