Inflammableness is a word that describes something that is prone to catch fire easily. Synonyms for inflammableness include flammability, combustibility, and ignitability. These words all describe the capacity of something to burn or ignite under certain conditions. Additionally, volatility and susceptibility also describe a similar tendency for something to ignite or burst into flames. It's important to note that these words can be used in different contexts. For example, the word "flammable" is used to label materials that are highly combustible and should be handled with care, whereas "ignitable" is used to describe something that can be ignited by a source of heat or flame.