The phrase "monochromatic colors" refers to colors that are made by varying the lightness or darkness of a single color. In other words, it means different shades of only one color. Full definition
An open - concept layout, nearly monochromatic color scheme and clean - lined furnishings lend the villa's interiors a look of contemporary luxury. (luxuryretreats.com)
I love how you use a kind of monochromatic color palette without it being dull. (blog.jennasuedesign.com)
His paintings are made of a series of small gestural markings; horizontal fields of monochromatic color. (western-project.com)