dump truck

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A heavy-duty truck having a bed that tilts backward to dump loose material.

Wiktionary

1. n. a heavy truck, for carrying loose, bulk cargo, having a hinged bed that allows the contents to be unloaded onto the ground

GNU Webster's 1913

1. n. a truck, usually with an open top, the carrying bopdy of which can be tilted so as to emptied its contents without handling.

WordNet 3.0

1. n. truck whose contents can be emptied without handling; the front end of the platform can be pneumatically raised so that the load is discharged by gravity