From Longman Dictionary of Contemporary Englishmotocrossmo‧to‧cross /ˈməʊtəʊkrɒs $ ˈmoʊtoʊkrɒːs/ noun [uncountable] TTCDSthe sport of racing motorcycles over rough land, up hills, through streams etc
Examples from the Corpus
motocross• Sean Cook's brilliant motocross form continues.• Today's senior championship contenders all started in the junior motocross events.• The wheels have Excel rims and Talon hubs, which are used by many top motocross teams.Origin motocross (1900-2000) motor + cross-country 