Red-green dichromacy is a type of color blindness where a person has difficulty telling red and green apart. There are several synonyms for this condition, such as deuteranopia, deuteranomaly, protanopia, and protanomaly. Deuteranopia and protanopia are more severe forms of red-green dichromacy, where a person cannot perceive any red or green at all. Deuteranomaly and protanomaly, on the other hand, are milder forms of color blindness where a person has a reduced ability to perceive red or green. These synonyms are often used interchangeably with red-green dichromacy to describe any form of color blindness that affects the red-green color spectrum.