I’ve lived in the US for more than a decade, and my English isn’t just fluent. You could say it’s hyperfluent—my diction, for one, is probably two standard deviations above the national average. But that still doesn’t mean “native.” I learned English just late enough to miss the critical window for acquiring a native accent. It’s a distinction that, depending on the era, could lead to certain complications. In the Book of Judges, the Gileadites are said to have used the word “shibboleth” to identify and slaughter fleeing Ephraimites, who couldn’t pronounce the sh sound and said “sibboleth” instead. In 1937, the Dominican dictator Rafael Trujillo ordered the death of any Haitian who couldn’t pronounce the Spanish word perejil (parsley) in what became known as the Parsley Massacre.