‘霓虹’ (ní hóng) literally means ‘secondary rainbow’ (霓) plus ‘rainbow’ (虹), referring to the colorful glowing lights produced by neon gas in sealed glass tubes. Though historically tied to the physics of light and atmospheric optics, the term is now used almost exclusively for commercial signage — especially the bright, eye-catching lights common in urban areas like Shanghai’s Nanjing Road or Tokyo’s Shinjuku district. Unlike ordinary bulbs, neon lights emit vivid reds, blues, and other colors depending on the gas mixture and phosphor coating.

In modern Chinese, ‘霓虹’ evokes urban energy, nightlife, and visual spectacle. It appears frequently in descriptive writing about cities, advertisements, and pop culture — for example, in phrases like ‘霓虹灯’ (ní hóng dēng, ‘neon light’) or ‘霓虹闪烁’ (ní hóng shǎnshuò, ‘neon lights flickering’). While the characters individually relate to natural rainbows, the compound word has no connection to weather or nature in everyday usage — it’s firmly rooted in artificial illumination and city life.