From Longman Dictionary of Contemporary Englishhorseboxhorse‧box /ˈhɔːsbɒks $ ˈhɔːrsbɑːks/ noun [countable] British EnglishTTC a large vehicle for carrying horses, often pulled by another vehicle SYN horse trailer American English
Examples from the Corpus
horsebox• Police found the man they were looking for in a horsebox.• Tom was one of several demonstrators who tried to block round a horsebox at the end of the meeting.• He drove the horsebox himself yesterday morning back to his base at Brandsby in North Yorkshire.• Twenty minutes sitting quietly in the horsebox beforehand gives you this opportunity.• The driver of the horsebox has been questioned and released on police bail. 