quicko: school

For Australians, "school" only refers to K-12.* Americans, consciously or not, use it to refer to any education whatsoever, right up through a Ph.D. This can be startling for Australians who could have sworn so-and-so was older than 18 to hear him suddenly speak of being in "school."

*Incidentally, the grades are referred to as "grade 9" instead of "ninth grade."