ˈgramz-, -aa(ə)mz- noun
or gram method
Usage: capitalized G
Etymology: after Hans C. J. Gram
: a method for the differential staining of bacteria by which they are treated with Gram's solution after being stained with gentian violet and are then treated with alcohol and washed in water with the result that certain species retain the dye while others are decolorized — see gram-negative , gram-positive