Chinois [sheen-WAH] n. Fine meshed conical strainer used to make smooth soups and sauces.
The word chinois (or chinoise) comes from the French for Chinese. In the kitchen it refers to a very fine mesh strainer that works like a food mill or food processor to strain and smooth soups and sauces. There is a similar tool called a China cap, which is shaped like a chinois, but is made purely of metal with small holes punched in the sides, which gives a slightly chunkier texture.
The two are often confused. Here's a China cap for sale, labeled as a chinois, and here's a chinois at Bed Bath and Beyond for $99.99.