The word 镜头 is formed through a conceptual and semantic fusion of its two components: 镜 (jìng), meaning "mirror" or "lens", and 头 (tóu), meaning "head" or "end". It originates from the physical apparatus of optical devices, where the 头 refers to the front-end part of the instrument that houses the 镜 or lens. Over time, this concrete meaning of "the head/lens of an optical device" (like a camera or telescope) expanded metaphorically to also represent the visual scene or shot captured through that lens, seamlessly blending the physical tool with the resulting image or perspective it produces.