rainbow; CL:道[dao4]
彩 (cǎi) · 11 strokes
Phonosemantic compound. 彡 represents the meaning and 采 represents the sound.
虹 (hóng) · 9 strokes
Phonosemantic compound. 虫 represents the meaning and 工 represents the sound. Originally was a pictograph of a creature, with two heads on each end, that resembled a rainbow.