2a. The Major Organelle of Eukaryotic cells, in which the Chromosomes are separated from the Cytoplasm by the Nuclear envelope. The Nucleus has 3 Parts the Nucleolus, the Chromatin, and the Nuclear envelope.
2b. A specialized, usually Spherical Mass of Protoplasm encased in a Double Membrane, and found in most living Eukaryotic cells, directing their Growth, Metabolism, and Reproduction, and functioning in the Transmission of Genic Characters.