The state or quality of being metameric; isomerism due to different bonding patterns in two substances having the same molecular formula. Contrasted with steroisomerism or optical isomerism. Also, the relation or condition of metameric compounds.
With inkjet prints, this generally refers to an effect where tones appear to change colour in different lighting conditions. Mostly noticeable with black and white prints made with coloured inksets, some tones that appear neutral when viewed under one light source will show a colour cast when viewed in a different light, e.g. daylight to tungsten light.
The phenomenon where two color samples appear to match under one light source, and differ under another. Two such samples are called a metameric pair.