n. The quality of having only one independent channel for conveying color information in the eye, i.e. total color blindness.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. complete color blindness; colors can be differentiated only on the basis of brightness
Word Usage
"The veterinary ophthalmology researchers said the disorder -- called congenital achromatopsia or rod monochromacy -- is a rare autosomal recessive genetic disorder with an estimated prevalence in human beings of about 1 in 50,000."