Littoral refers to the coast of an ocean or sea, or to the banks of a river, lake or estuary. It is usually use as an adjective, but may also be used as a noun. The littoral zone extends from the high water mark, which is rarely inundated, to shoreline areas that are permanently submerged. It includes the intertidal and sublittoral zones. The word 'littoral' is derived from the Latin noun litus, litoris, meaning "shore". (The doubled 't' is a late mediaeval innovation and the word is sometimes seen in the more classical-looking spelling 'litoral'.)