A topsail is the second square sail up a mast in a sailboat. Topsail may also refer to:
In geography Canada Topsail, Newfoundland and Labrador, a community in Conception Bay South, Newfoundland and Labrador, Canada Topsail (electoral district), a former provincial electoral district in Newfoundland and Labrador
United States Topsail Island, one of the barrier islands on the southern coast of North Carolina, USA Topsail Beach, North Carolina, a community on the southern part of Topsail Island North Topsail Beach, North Carolina, a community on the northern part of Topsail Island
In other uses Topsail, a software project originating with U.S. Department of Defense's Information Awareness Office and later moved for further development with the National Security Agency See also Edward Topsell (1572–1625), English author