Soft coal is a type of coal with a low carbon content and high moisture content, also known as lignite. It is commonly used in power generation and other industrial uses due to its high energy content. If you are searching for synonyms to this term, some of them could be brown coal, peat, degraded coal, black lignite, or non-agglomerating coal. These are all types of low-quality coal with different properties and applications. Due to its low calorific value, soft coal tends to produce less heat per unit of volume compared to higher-grade coal, but it is abundant and affordable, which makes it the preferred option in many countries.