Do you know what a necklace is? It's a piece of jewelry that goes around your neck. Well, a halterneck is like a necklace that helps hold up a dress or a shirt. It's a strap that goes around the back of your neck and comes down to attach to the front of the shirt or dress. This way, the shirt or dress doesn't fall down and it looks stylish too! It's called a halterneck because it looks like a horse's halter, which is a special kind of rope that goes around the horse's neck and helps control it.