Inscrutable means extremely difficult to understand or interpret. When something is inscrutable, you can't figure out what it means no matter how hard you try. A teacher's inscrutable expression after you turn in a project gives no hint whether she loved it or hated it. An inscrutable smile reveals nothing about what the person is really thinking.

The word often describes people whose thoughts and feelings remain hidden. Your friend might have an inscrutable look on her face when she's keeping a secret. A poker player maintains an inscrutable expression so opponents can't tell if she has good cards or bad ones.

Inscrutable can also describe mysterious writing, puzzling ancient artifacts, or confusing instructions. When archaeologists discover inscrutable symbols carved into a temple wall, they mean the markings are so mysterious they can't decipher what they represent.

The word usually carries a sense of fascinating mystery rather than simple confusion. An inscrutable person isn't just very hard to read; they can seem almost impossible to read.