/ Dictionary / Index S St. Lawrence: Meaning and Definition of Find definitions for: St. Lawrence Pronunciation: [key] a river in SE Canada, flowing NE from Lake Ontario, forming part of the boundary between New York and Ontario, and emptying into the Gulf of St. Lawrence. 760 mi. (1225 km) long. an arm of the Atlantic between SE Canada and Newfoundland. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. St. Laurent St. Lawrence Seaway Related Content Daily Word Quiz: rustic Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language