Definition of spectral

The word "spectral" has its roots in Latin. The Latin word "spectrum" means "something seen" or "appearance," which is derived from the verb "specere," meaning "to see." In the 14th century, the Latin word "spectrum" was borrowed into Middle English as "spectre," meaning "ghost" or "apparition." This referred to the immaterial and often frightening nature of a ghost or specter. Over time, the spelling was changed to "spectral," and the meaning expanded to convey other senses of "something seen," such as a phenomenon or a quality that is visible or perceivable. In modern English, the word "spectral" is often used in physics, especially in the context of spectroscopy, to describe the distribution of light or other forms of electromagnetic radiation as a function of wavelength or frequency.