Definition of "horsebox"

horsebox

noun
plural horseboxes
1. (UK) A motor vehicle for transporting horses.
2. A container for transporting horses in, whether by road, rail, or sea.
3. (UK, rail transport, obsolete) A van-type railway vehicle specially built for the carriage of horses.
  Quotations
  On October 31 [...] Laira "Grange" No. 6871 passed through Wolverhampton with a Holyhead-Didcot horsebox special.
  1960 January, “Motive Power Miscellany: Western Region”, in Trains Illustrated, page 58