(n) a habit-forming drug that is not addictive but its use may lead to the use of other addictive drugs, Example:one college athlete recently called beer a gateway drug for young people
(n) the largest city in Missouri; a busy river port on the Mississippi River near its confluence with the Missouri River; was an important staging area for wagon trains westward in the 19th century, Syn. Gateway to the West, St. Louis
The Collaborative International Dictionary of English (GCIDE) v.0.53 Collaborative International Dictionary (GCIDE)
n. A passage through a fence or wall; a gate; also, a frame, arch, etc., in which a gate in hung, or a structure at an entrance or gate designed for ornament or defense. [ 1913 Webster ]