A mannequin is a human-like figure that's usually used to display clothing in a store. A mannequin in a department store window can look quite normal, but a mannequin in someone's home can look downright creepy.
Any store that sells clothes is likely to have at least a few mannequins, so shoppers can see what dresses and sweaters and hats look like on a (fake) person's body. Another kind of mannequin, more often called a "dressmaker's dummy" is helpful to someone who's sewing a skirt or piecing together a suit. Still other mannequins are used to practice emergency techniques, from CPR to water rescues by the Coast Guard.