Spectrum, Spectra, Spectre
I’m not feeling especially peevish just now, truly, but I will say that a linguistic habit I’m running into more frequently is beginning to rub me the wrong way. That habit is the misuse of the word “spectra”.
I hear many people using the word “spectra” as the singular form rather than the word “spectrum”. Spectra is the plural form of the word spectrum.
The spectre of spectra as spectrum shines like a specular glare from a speculum mirror in the corner of my consciousness.