主虹[shuniji] primary rainbow
虹彩[kousai] iris (of the eye)
虹色[nijiiro] rainbow-colored
副虹[fukuniji] secondary rainbow
虹霓[kougei] rainbow

白虹[hakkou] white rainbow
虹鱒[nijimasu] rainbow trout (Oncorhynchus mykiss)
虹彩異色症[kousaiishokushou] heterochromia iridis
虹梁[kouryou] arched beam used in shrine and temple construction