segmentation

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Division into segments.

from The Century Dictionary.

• noun The act of cutting into segments; a division into segments; the condition of being divided into segments; the manner in which a segmented part is divided.

from the GNU version of the Collaborative International Dictionary of English.

• noun The act or process of dividing into segments; specifically (Biol.), a self-division into segments as a result of growth; cell cleavage; cell multiplication; endogenous cell formation.
• noun (Biol.) the cavity formed by the arrangement of the cells in segmentation or cleavage of the ovum; the cavity of the blastosphere. In the gastrula stage, the segmentation cavity in which the mesoblast is formed lies between the entoblast and ectoblast. See Illust. of Invagination.
• noun (Biol.) the body formed by fusion of the male and female pronucleus in an impregnated ovum. See the Note under Pronucleus.
• noun (Biol.) the process by which the embryos of all the higher plants and animals are derived from the germ cell. In the simplest case, that of small ova destitute of food yolk, the ovum or egg divides into two similar halves or segments (blastomeres), each of these again divides into two, and so on, thus giving rise to a mass of cells (mulberry mass, or morula), all equal and similar, from the growth and development of which the future animal is to be formed. This constitutes regular segmentation. Quite frequently, however, the equality and regularity of cleavage is interfered with by the presence of food yolk, from which results unequal segmentation. See Holoblastic, Meroblastic, Alecithal, Centrolecithal, Ectolecithal, and Ovum.
• noun (Biol.) the blastosphere, or morula. See Morula.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The act or an instance of dividing into segments.
• noun The state of being divided into segments.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun (embryology) the repeated division of a fertilised ovum
• noun the act of dividing or partitioning; separation by the creation of a boundary that divides or keeps apart