Definition

Noun: - One of two siblings born from a single fertilized egg that splits: A "monozygotic twin" is one individual of a pair of twins who originate from a single zygote (fertilized egg). This egg splits into two separate embryos early in development. - Genetically identical sibling: Because they develop from the same zygote, monozygotic twins share virtually identical genetic material.

Usage

• The term is used in scientific, medical, and general contexts to specify the type of twinning and the genetic relationship between the twins.
• It is often contrasted with "dizygotic twins" (fraternal twins), who develop from two separate fertilized eggs.

Examples

Advanced Usage

• "Monozygotic twinning": The process or event where a single zygote divides to form two embryos.
  • The causes of monozygotic twinning are not fully understood.
• Used attributively (as an adjective) in compound nouns like "monozygotic twin study" or "monozygotic twin pair."
  • Research involving monozygotic twin pairs is valuable for genetics.

Variants and Related Words

• Identical twin: The common, non-technical synonym for "monozygotic twin."
• Dizygotic twin (n): The technical term for a fraternal twin, which develops from a separate fertilized egg.
• Zygote (n): The cell formed by the union of a sperm and an egg; a fertilized egg.

Synonyms

• Identical twin: The most frequent synonym in everyday language.

Notes on Meaning

• While "monozygotic twins" are often called "identical," minor genetic differences can occur after the egg splits. They are always of the same sex.
• The term precisely describes the biological origin (one zygote), whereas "identical" describes the observable genetic similarity.

Noun

1. either of two twins developed from the same fertilized ovum (having the same genetic material)