(mineralogy) A mineral crystal whose interior space is empty

(archaic) The game of hopscotch.

plural of leaf-hopper

A rake in a mill, moving in a circle to spread meal for drying, and to draw it over an opening in the floor, through which it falls.

plural of Johnny Hopper

(UK, Cockney rhyming slang) A police officer.

plural of hopper car

(rail transport, US) A railroad freight car which is used to transport bulk materials in a hopper, the load being usually discharged through the bottom of the car.

(rail transport, UK) a railway goods wagon which is used to transport bulk materials in a hopper, the load being usually discharged through the bottom of the wagon.

plural of hopper wagon