Violet
The word rainbow is a noun. A rainbow is a multicoloured arch that appears in the sky.
Yes. Rainbows are formed when the sun and water meet and water is nature and so is the sun so yes rainbows are part of nature
No.
A rainbow is part of Nature. There is no "they".
or you may be thinking of your foot arch
Your foot
the outer part of a tree trunk
A rainbow shows the optical (visible) part of the electromagnetic spectrum; infrared (if you could see it) would be located just beyond the red side of the rainbow with ultraviolet appearing just beyond the violet end. The way to rembember the colors of the rainbow are Roy G Biv, meaning Red, orange, yellow, green, blue, indigo, and violet.
Rainbows can occur anywhere around the world, but they are most commonly seen in tropical regions with frequent rain showers and sunlight, such as Hawaii or the Caribbean.
Outer is an adjective
Rubor, dolor and calor are three signs of infection. That mean redness, pain and hot part, respectively.
Laminectomy is the medical term meaning surgical removal of part of a vertebral arch.