noun.
In bot, a name proposed for that portion of the substance of the nucleus which is readily colored by staining agents.
noun.
In zoology, that portion of the substance of an ovum which has a special affinity for coloring matter and readily becomes colored; chromophilous protoplasm, which in the process of maturation of the ovum forms various colored figures, as disks and threads: the opposite of achromatin.
noun.
In cytology, that portion of the cell-nucleus in animals and plants which takes on a deep color in certain stains (carmine, hematoxylin, etc.): opposed to achromatin.