Oil is a smooth, thick liquid that is used as a fuel and for making the parts of machines move smoothly. Oil is found underground.

If you oil something, you put oil onto or into it, for example to make it work smoothly or to protect it.

Oil is a smooth, thick liquid made from plants and is often used for cooking.

Oil is a smooth, thick liquid, often with a pleasant smell, that you rub into your skin or add to your bath.

Oils are oil paintings .

When an artist paints in oils, he or she uses oil paints.

If you pour oil on troubled waters, you try to calm down a difficult situation.

If someone or something oils the wheels of a process or system, they help things to run smoothly and successfully.