The word 火车 (huǒchē, meaning "train") is formed through a direct conceptual combination of its two component characters: 火 (huǒ), meaning "fire", and 车 (chē), meaning "vehicle" or "cart". It is a compound where the first element describes the defining characteristic or power source of the second. Historically, this term originated with the introduction of steam locomotives, which were quite literally "fire-vehicles", as they were powered by coal-fired boilers producing steam. Thus, the word paints a simple, descriptive picture of a "vehicle that uses fire".