Dictionary.net

[Greek] Appl. substances characterised by metachromasy; appl. granules of reserve food substances which stain with basic dyes, in bacteria and algal cells.

[Greek] Changing in color. M. bodies, peculiar granules brought out in certain bacteria (e. g., Bacillus diphtheria) by staining. M. staining, staining in which the pigment imparts different hues to different tissue-elements.

Pertaining to, or affected with metachromatism.