A school that only admits male or female students. Very much a Truth in Television: Many (but not all) schools run by religious organizations are single-sex. At least, once the students are old enough for messing around to occur -- many Roman Catholic and other private high schools are still single-sex. Likewise boarding schools tend to be single-sex. Many educators in such institutions defend the practice not just from the prudish attitude that one might expect, but some more practical concerns; female students, for example, can be shown to perform better without male students around as they're more likely to engage the subject material as they are less likely to be afraid of being perceived as too smart to attract sexual attention. There is, of course, a feeling in many quarters that hor