"Gateway to the West" means: A nickname for St. Louis, Missouri, referencing the city's historical role as the jumping-off point for westward expansion in the United Sta.... This is a fairly neutral word with no inherent risk attached. There is no real cause for parental concern; it is descriptive vocabulary rather than something dangerous. If your child uses it, context will usually make the meaning clear. A brief, curious question about where they heard it is generally enough to know whether to follow up.