Early 17th century (denoting a tract of open country): from French campagne 'open country', via Italian from late Latin campania, from campus 'level ground' (see camp¹). The change in sense arose from an army's practice of ‘taking the field’ (i.e. moving from a fortress or town to open country) at the onset of summer.

• Latin campania meant ‘open countryside’ and was based on campus ‘a field’. It is the source of English campaign, which was originally a tract of open land and is a close relative of French champagne, both an area of open country and the winemaking region. The connection between countryside and fighting is that armies tended to spend the winter in a fortress or town, ‘taking the field’ in summer. Hence the countryside became associated with military manoeuvres. Camp (early 16th century), which is also from Latin campus was similarly used in Latin not only to mean ‘a field, level ground’ but, more specifically, ‘an open space for military exercises’—the most famous one was the Campus Martius, or Field of Mars, in Rome. This developed into the idea of a place where soldiers are housed. Campus itself came into English in the 18th century as the term for university or college grounds. See also champion