Burnt residue refers to the leftover material that remains after something has been burned or charred. There are many synonyms for this term including ash, cinders, soot, char, and carbon. Ash is a light, fine residue that is often seen after the burning of wood or paper. Cinders are larger, chunkier pieces of burnt material, often seen after the burning of coal. Soot is a black, powdery substance that forms when organic matter is burned incompletely. Char is a dark, carbon-rich residue that remains after something has been burned at high temperatures. Carbon is a gray-black substance that is formed when organic matter is burned completely. All of these terms can be used interchangeably with burnt residue depending on the context.