analogous
Colors that are adjacent to each other on the color wheel
complementary
Colors that are opposite each other on the color wheel
triadic
Three colors equally spaced around the color wheel
split complementary
A base color and two colors adjacent to its complement
tetradic
Two pairs of complementary colors
square
Four colors evenly spaced around the color wheel
monochromatic
Different shades, tones, and tints of the same base color