The word that stands out from the group is "oil" because it is the only word that is not a dairy product. Let's analyze each option in detail:

a) Curd: Curd is a dairy product that is made by curdling milk with an edible acidic substance like lemon juice or vinegar. It is commonly used in various cuisines for its creamy texture and tangy taste.

b) Butter: Butter is another dairy product that is made by churning cream or milk to separate the butterfat from the buttermilk. It is widely used in cooking, baking, and as a spread on bread or toast.

c) Oil: Oil, in this context, refers to cooking oil, which is typically derived from plants or seeds. It is used for frying, sautéing, and as a base for dressings or marinades. Unlike curd and butter, oil is not a dairy product but an essential ingredient in cooking.

d) Cheese: Cheese is a dairy product that is made by coagulating milk and then separating the curds from the whey. It comes in various textures and flavors and is used in a wide range of dishes, from sandwiches to pasta.

In summary, while curd, butter, and cheese are all dairy products, oil stands out as it is not derived from milk but is instead a cooking ingredient obtained from plants or seeds.