Translation guide
This guide explains how to express the concept of 'twin' in Japanese, covering both people and objects, with a focus on natural usage and common pitfalls.
Referring to a twin brother or sister, or the state of being twins.
The most common and general word for 'twins'. Can refer to both identical and fraternal twins. Use with counters or possessive structures to specify.
She is a twin.
I have a twin older brother.
Specifically 'twin sibling' (brother/s). More explicit than 双子 alone.
He has a twin brother.
Specifically 'twin sisters'. Use when gender is known and relevant.
Those twin sisters get along very well.
Technical/medical term for 'identical twins'. Not used in everyday conversation.
Identical twins are genetically identical.
Technical/medical term for 'fraternal twins'.
Fraternal twins are like regular siblings.
Describing two identical or closely related objects, such as beds, towers, or engines.
Pattern meaning 'twin [noun]', used for objects that come in identical pairs. Common in names of landmarks or products.
twin towers
This ship is equipped with twin engines.
Loanword from English, often used in product names or hotel rooms (e.g., twin room). Not used for people.
Means 'twin-engine' (literally 'double launch'), used in aviation or automotive contexts.
Expressing the idea of two things together, often in abstract or compound terms.
Means 'double' or 'twofold'. Used in words like 二重人格 (split personality) or 二重構造 (dual structure). Not for siblings.
The plan has a twin purpose.
Prefix meaning 'both' or 'pair', used in formal compounds like 双方 (both sides) or 双方向 (bidirectional). Rarely used alone.
two-way communication
The loanword ツイン is only for objects or hotel rooms. Using it for a twin sibling sounds unnatural. Stick to 双子 for people.
双子 is the everyday word for twins. 双生児 is a formal/medical term, rarely used in conversation. Use 双子 unless you're writing a scientific paper.
I booked a room with twin beds.
双発機
twin-engine aircraft