Genoa
From MITNA
A genoa, or "jenny", is a large foresail on a sloop or similar sailboat, much like a jib sail, but larger.
Jibs and genoas are often described by their size relative to a boat's foretriangle. The foretriangle is the triangle created by the mast, the forestay, and the deck between the mast and the bow. Technically, a jib sail's area is always less than the size of the foretriangle. A genoa is larger than the foretriangle and the luff of the sail reaches back aft of the mast. In practice, the terms "jib" and "genoa" are often interchanged when describing a genoa.
Genoas are common on ocean-going sailboats. They usually have a roller-furling mechanism on the forestay to allow for easy deployment and furling of the large sail.