Loaf-sugar broken into lumps, or cut into small cubes.(noun)
The Century Dictionary (Public Domain)
Use "lump-sugar" in a sentence
"Mr. Commissioner Pordage kept in a red-and-black japanned box, like a family lump-sugar box, some document or other, which some Sambo chief or other had got drunk and spilt some ink over (as well as I could understand the matter), and by that means had given up lawful possession of the"
"It looked as if a ton of grey lump-sugar had been tipped across the hangar floor in the chance shape of an aeroplane."
"To encourage the coffee somewhat the Deacon "dug" his front foot into the lump-sugar bowl and extracted a couple of aces; and the other mimics followed suit with two, three, and four spots."