bicolour vs two-tone

bicolour

adj

  • Having two colours 

noun

  • A flower, cat etc., that has two colours. 

  • A flag with such colours, consisting of two stripes that are either vertical or horizontal. 

two-tone

adj

  • Having two colours or shades. 

  • Giving two different sounds, either alternately or simultaneously. 

How often have the words bicolour and two-tone occurred in a corpus of books? (source: Google Ngram Viewer )