The term used to describe the zygote is the fertilized egg. A zygote is formed when a sperm cell fertilizes an egg cell, marking the beginning of a new organism. This single cell contains all the genetic information necessary to form a new individual.
After fertilization, the zygote undergoes a series of cell divisions, known as cleavage, to form a multicellular embryo. This process is the first step in the development of a new organism and is crucial for the continuation of species.