deficiency.
Female color blindness is about 1 in 200.
Total color blindness -- not seeing any colors -- is extremely rare. Way less than 1 in 1000.
Red/green deficiencies are the most common. Like I said, about 1 in 12 males. I have that deficiency, . . . hardly ever give it a thought.
I know that red and green are on opposite sides of the color wheel chart. I can tell the two colors apart from each other fairly easily but they don't look like opposites at all. I even think they're pretty colors but I know I don't see them normally.
People with red/green deficiencies will sometimes have a hard time telling green from brown and purple from blue. Mostly it's just a fun conversation topic. It will be cool though in the next life to eventually see colors the way they really are.