boarding school vs prep school

boarding school

noun
  • A school which provides board and lodging as well as tuition, with students going home at weekends or between terms. 

  • A boarding school in which a dominant or colonial culture whitewashes a subordinate one de-culturizing the students of their native language, customs, religion, and culture. 

prep school

noun
  • A private or public school intended to prepare its students to get into prestigious universities. 

  • A private primary school which prepares its pupils for the common entrance examination most commonly at the age of thirteen, and subsequent entry into public school. 

How often have the words boarding school and prep school occurred in a corpus of books? (source: Google Ngram Viewer )