fluorescein has definitions from the fields of chemistry,color
[ noun ] (chemistry,color) a yellow dye that is visible even when highly diluted; used as an absorption indicator when silver nitrate solution is added to sodium chloride in order to precipitate silver chloride (turns pink when no chloride ions are left in solution)

Used in print

(A. N. Nagaraj and L. M. Black, "Localization of...)

In attempting to improve specificity of staining , the fluorescein labeled antisera used in both direct and indirect methods were treated in one of several ways : ( 1 ) They were passed_through Dowex-2-chloride twice and treated with acetone insoluble powders ( Coons , 1958 ) prepared from mouse liver or from healthy sweet_clover stems or crown_gall tissue produced by Agrobacterium_tumefaciens ( E._F._Smith + Townsend ) Conn , on sweet_clover stems .

Schramm and Rottger ( 1959 ) did not report any such nonspecific staining of plant_tissues with fluorescein isocyanate labeled antiserum to tobacco_mosaic_virus .