Real Dictionary

white sauce
variable noun: White sauce is a thick white sauce made from milk, flour, and butter. Meat, fish, or vegetables are often cooked in or served in white sauce.

white sauce in American English
a cooked sauce for vegetables, meat, fish, etc. made of fat or butter, flour, milk, cream, or stock, and seasoning
a sauce made of butter, flour, seasonings, and milk or sometimes chicken or veal stock; béchamel

white sauce in British English
noun: a thick sauce made from flour, butter, seasonings, and milk or stock