moellon

from The Century Dictionary.

• noun Rubble-stone, sometimes used in architecture, set in mortar, for such uses as filling between the facing-walls of a structure or in the spandrels of a bridge.
• noun In tanning, partly oxidized oil recovered by expression from skins in the process of oil-tanning.

from the GNU version of the Collaborative International Dictionary of English.

• noun Rubble masonry.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun rubble masonry