rainbow
虹 centers on the rainbow: the arc of colors that appears in the sky after rain.
虹 combines 虫 (insect/serpent) and 工 (which likely contributes the sound コウ). In ancient Chinese thought, a rainbow was seen as a serpent-like creature, hence the 虫 component.
A rainbow is like a giant colorful insect (虫) arching across the sky, with its shape reinforced by the straight 工 lines.
For コウ, imagine a rainbow forming a perfect arc over a calm koi pond: koi -> コウ, and the rainbow's colors reflect on the water.
rainbow
iris
rainbow trout (Oncorhynchus mykiss)
primary rainbow
secondary rainbow
reflection rainbow
evening rainbow
moonbow; lunar rainbow; whitish rainbow cast by moonlight; lunar bow; space rainbow
morning rainbow
white rainbow
to die (of a pet); to cross the rainbow bridge
iridocyclitis
iritis
heterochromia iridis; eyes differing in colour (color)
iris recognition; iris identification
Kogi Corporation
arched beam used in shrine and temple construction
rainbow-colored; rainbow-coloured
rainbow
supernumerary rainbow