一卵性(いちらんせい)

いちらんせい
noun
identical (twins); monozygotic
1. identical; monozygotic
Derived from a single fertilized egg, used primarily to describe identical twins who share the same genetic material.
一卵性(いちらんせい)双生児(そうせいじ)。
Identical twins.
二人(ふたり)は一卵性(いちらんせい)の双子(ふたご)だから見分(みわ)けがつかない。
The two are identical twins, so I can't tell them apart.
一卵性(いちらんせい)の双子(ふたご)は遺伝子(いでんし)が同(おな)じだ。
Identical twins have the same genes.

一卵性(いちらんせい) is a scientific term meaning "monozygotic" — derived from a single fertilized egg. It is almost always used as a modifier before 双子(ふたご) or 双生児(そうせいじ).

ETYMOLOGY:
A compound of 一(いち) (one) + 卵(らん) (egg) + 性(せい) (nature/type).

COMMON EXPRESSIONS:

  • 一卵性(いちらんせい)双生児(そうせいじ): identical twins (formal/medical)
  • 一卵性(いちらんせい)の双子(ふたご): identical twins (everyday)

CONTRAST:

  • 一卵性(いちらんせい): identical/monozygotic (from one egg)
  • 二卵性(にらんせい): fraternal/dizygotic (from two eggs)

USAGE:
双子(ふたご) alone means "twins" without specifying type. 双生児(そうせいじ) is the more formal medical term for twins. In everyday conversation, 一卵性(いちらんせい)の双子(ふたご) is more common than 双生児(そうせいじ).

general
Added 2026.1.29 15:16 · Revised 2026.4.5 9:56
08500/08959_ichiransei