littoral (adj.) Look up littoral at Dictionary.com
"pertaining to the seashore," 1650s, from Latin littoralis "of or belonging to the seashore," from litus (genitive litoris) "seashore, coast" (compare Lido), from Proto-Italic *leitos, of unknown origin, possibly from PIE root *lei- "to flow," but de Vaan finds a better candidate in the PIE root *leit- (2) "to go forth" (see lead (v.1)), with sense evolution "the going away," hence "the edge."

The noun is first recorded 1828, from Italian littorale, originally an adjective, from Latin littoralis.