A lot vs. Alot: 9 Grammatical Pitfalls
1610s, "apparition, specter," from Latin spectrum "appearance, image, apparition," from specere "to look at, view" (see scope (n.1)). Meaning "band of colors formed from a beam of light" first recorded 1670s.
spectrum spec·trum (spěk'trəm)
n. pl. spec·trums or spec·tra (-trə)
The distribution of a characteristic of a physical system or phenomenon, especially the distribution of energy emitted by a radiant source arranged in order of wavelengths.
The color image presented when white light is resolved into its constituent colors: red, orange, yellow, green, blue, indigo, violet.
The plot of intensity as opposed to wavelength of light emitted or absorbed by a substance, usually characteristic of the substance and used in qualitative and quantitative analysis.
The distribution of atomic or subatomic particles in a system, as in a magnetically resolved molecular beam, arranged in order of masses.
The group of pathogenic organisms against which an antibiotic or other antibacterial agent is effective.
Plural spectra (spěk'trə) or spectrums