Definitions for "Monozygotic twins"
Keywords:  twin, zygote, ovum, dizygotic, egg
Two individuals derived from a single fertilized egg and therefore genetically identical.
twins which have been produced by the division of a single zygote. Each twin has an identical genotype. As such, these individuals are often referred to as "identical twins". While each twin begins with the same set of genetic information, the effect of the environment within which each individual grows up can cause differences in how their genetic make-up is expressed.
twins (identical) produced by division from a single zygote. Twins therefore share the same genetic makeup. Note dizygotic twins arise from separate fertilizations of different eggs. (More? Week 1 Twinning)