Mobile homes or recreational vehicles designed to be towed by another vehicle, or previews of upcoming movies shown before a feature film.
From Middle English 'trailen' meaning 'to drag behind,' derived from Old French 'trailler.' The movie preview sense emerged in the 1930s because they originally 'trailed' after the main feature.
Movie trailers were originally shown after the film ended, but audiences would leave before seeing them, so studios moved them to the beginning. The term stuck even though they no longer 'trail' anything!
Complete word intelligence in one call. Free tier — 50 lookups/day.