Definition from Usability First
“An inability to distinguish certain color combinations. About 8% of males and 0.5% of females are colorblind in some fashion, so it is common enough to be a highly-significant factor in design.”
Going further
I've curated 400+ definitions just like this one in a tiny dictionary. In this glossary you can easily access, search and understand 400+ terms that service designers and other innovators use.