third class noun 3third-class adjective 1forms 1 noun3 •A class of accommodation in travel below second class. •(UK, historical) The cheapest accommodation on a train or ship.Mail trains are limited to first and second class passengers, but on the mixed trains third class is also provided, and this is patronised exclusively by natives. — 1940 •(US) A reduced-rate mail service for printed matter. third-class adjective1 •Most inferior in quality or standing.Travelling third-class isn't just slow, it's painful. formsthird classes
