What is the plural number of 'Spectrum'?

• Spectra or Spectrums হচ্ছে Spectrum এর plural form.• Spectrum (noun): English Meaning: A band of colours, as seen in a rainbow, produced by separation of the components of light by their different degrees of refraction according to wavelength.Bangla Meaning: বর্ণচ্ছটা; বর্ণালি; (লাক্ষণিক) বিস্তৃতি, বিস্তৃত পরিসর বা ধারা: Example sentence: The whole spectrum of recent political development.Source:1. Oxford Learner's Dictionary.2. Accessible Dictionary by Bangla Academy.