Translation guide
In Japanese, expressing 'cohabitation' depends on the nuance: living together as romantic partners (often before marriage), sharing a residence for practical reasons, or the legal/sociological concept. The most common and natural term for unmarried couples living together is 同棲 (どうせい).
The speaker wants to say that a couple lives together without being married, often implying a romantic relationship and shared domestic life.
The standard, neutral term for an unmarried couple living together. It strongly implies a romantic relationship and is widely understood.
彼氏と同棲しています。
I'm living with my boyfriend.
結婚する前に同棲したい。
I want to live together before getting married.
A more general phrase meaning 'living together.' It can be used for any cohabitation, but in context often implies a romantic relationship. Less direct than 同棲.
彼女と一緒に住んでいます。
I live with my girlfriend.
Refers to a common-law marriage or de facto marriage. It implies a committed, marriage-like relationship without legal registration. More formal and legalistic than 同棲.
事実婚のカップルが増えている。
The number of common-law couples is increasing.
The speaker wants to say that people live in the same house or apartment for convenience, cost-sharing, or companionship, without romantic implications.
The most common term for sharing a house or apartment with non-romantic housemates. Often used among young people and in urban areas.
友達とルームシェアしています。
I share an apartment with a friend.
A general term for living together in the same dwelling. It can refer to family members, friends, or even strangers. Context clarifies the relationship. More formal than ルームシェア.
Specifically refers to living in a share house, a type of communal housing where residents have private rooms but share common areas. Popular among young people and foreigners.
東京でシェアハウスに住んでいます。
I live in a share house in Tokyo.
The speaker is discussing cohabitation as a social phenomenon, legal status, or demographic trend, often in formal or academic contexts.
Used in sociological discussions to refer to unmarried cohabitation. It is the standard term in surveys and reports.
若者の同棲に対する意識が変わってきた。
Young people's attitudes toward cohabitation have changed.
同棲 (どうせい) specifically implies an unmarried romantic couple living together, often with a nuance of trial marriage or pre-marriage arrangement. 同居 (どうきょ) is a broader term for any shared living situation, including family, friends, or even strangers. Using 同棲 for non-romantic roommates would be incorrect and potentially embarrassing.
兄と同居していますが、同棲ではありません。
I live with my brother, but we're not a cohabiting couple.
The English word 'cohabitation' can sound formal or legalistic. In Japanese, directly translating it as コハビテーション is rarely natural outside academic papers. Use 同棲 for romantic partners and 同居 or ルームシェア for other situations.
I live with my parents.
見知らぬ人と同居するのは大変だ。
Living with strangers is tough.
A direct loanword from English, used in academic or technical writing. Not common in everyday conversation.
コハビテーションの増加は少子化と関係がある。
The increase in cohabitation is related to the declining birthrate.