in sailing ships, triangular sail rigged to a stay extending from the foremast, or foretopmast, to the bowsprit or to a spar, the jibboom, that is an extension of the bowsprit. The jib is first known to have been used on one-masted vessels. Its use began to spread about 1600 and extended to larger war vessels about 1700. Jibs proved handy in helping to steer and were much valued—e.g., on the square-rigger, as a means of better close-hauled sailing and of setting extra sail with comparatively little labour demand. In some ships the number of jibs reached five or more, and often the jibboom itself required an extension, the flying jibboom, to carry them.

Most modern sailboats lack a bowsprit or a jibboom, and the lower corner of the jib is attached to a fitting on the hull near the bow.