"Complementary colours" refers to colors that are opposite each other on the color wheel. They tend to enhance each other when placed together and create a contrast that is visually appealing.
Sentences with «complementary colours»
Bring in artwork in complementary colours to add personality to your scheme. (idealhome.co.uk)
They're connected by theme, certainly, but there's also a use of complementary colours. (creativeboom.com)
Just make sure you're using complementary colours and patterns to tie the room together. (styleathome.com)