noun
(uncountable) The backs of camels.
(countable) A flexible water container worn on the back.
(countable) A house with a second storey that does not completely cover the ground floor.
(countable, rail transport) A railway locomotive that has its cab in the middle as opposed to at the end.
(countable) A sofa or chair whose back has a raised middle part.
(uncountable) A type of rubber used in tyre restoration.
(countable) One or more hump-shaped hills on a straight portion of rollercoaster track, designed to lift riders out of their seats and provide a feeling of weightlessness.