aurora-colored (US) / aurora-coloured vs polychromate

aurora-colored (US) / aurora-coloured

polychromate

adj

  • Composed of many colours 

noun

  • A salt or ion composed of multiple chromate groups 

How often have the words aurora-colored (US) / aurora-coloured and polychromate occurred in a corpus of books? (source: Google Ngram Viewer )