A type of knitted top similar to a sweater, but without sleeves, usually with a low-cut v-shaped neckline. Unlike a sleeveless sweater, a sweater vest is usually worn over a shirt, typically a dress shirt, rather than being worn by itself. A sweater vest also never has a turtleneck. If you can't tell whether or not it has sleeves, then assume it is a sweater. If it has buttons in front, it's a cardigan vest instead.