spectrum

释义：“光谱”，最初被牛顿用来描述白光被棱镜分解后产生的颜色带，现在也常引申体现渐变的“一系列状态”。

例句：
The visible, "rainbow" spectrum is the portion of the electromagnetic spectrum that is visible as light to the human eye.
At the other end of the spectrum, some employers will see the maximum increase of about $81 per worker per year.