noun
Etymology: from Nile, river in Africa
1. often capitalized N : a light bluish green, greener and deeper than average aqua green (sense 1), bluer and paler than average turquoise green, and bluer and stronger than robin's-egg blue (sense 2)
2. or nile blue A usually capitalized N & sometimes capitalized B : an oxazine dye used chiefly in the form of the sulfate as a biological stain (as for staining neutral fat red in the presence of dilute sulfuric acid)