1. coal dust or slack coal; the waste or inferior coal left after screening
Usage: chiefly British; mining industry term
2. the hollow stem or jointed stalk of grasses, especially between the joints or nodes
Usage: botany; also called culm node or culm internode

Examples

• The miners separated the culm from the higher-grade coal at the processing plant.
• Culm was often burned as a cheap fuel source in industrial areas.
• The bamboo's culm is remarkably strong and flexible.
• Farmers used culm waste to fill low-lying areas on their land.
• The hollow culm of the grass swayed in the wind.