Used in printing, the color model abbreviation “CMYK” represents the colors cyan, magenta, yellow and what?

The K stands for "Key" which actually means black.

Great answer explanation. I appreciate hearing why it's K and not B, makes sense once it's explained

black ink isn't required due to impurities in the inks, it's required because there's limits to how much light the ink can absorb , given its got to stain white paper . . and the spectrum of the ink isn't perfect

K stands for Key, and is used so as not to be confused with other colours.

I am confused!!