sister
sister — noun
1. a female sibling — the girl in a family who shares both parents, or one parent,
a female sibling — the girl in a family who shares both parents, or one parent, with another child.
Adaeze and her younger sister shared a bedroom until she finished high school.
possessive determiner + sister: 'her younger sister'
Dewi's older sister taught her how to ride a bicycle when she was six.
possessive + 'older sister'
Mira's baby sister just learned to walk last month.
Salma waved goodbye to her sister at the train station before moving to Tokyo.
- older sister
- younger sister
- little sister
- big sister
- twin sister
- baby sister
- half-sister
- stepsister
- sister of the bride
- sibling
gender-neutral term; can refer to a brother or a sister
- half-sister
specifically a sister who shares one parent, not both
- brother
male sibling
Grammar Patterns
my/her/his sister
older/younger/little/big sister
twin/half/stepsister
Usage Note
Commonly preceded by a modifier such as 'older', 'younger', 'little', 'big', 'twin', 'half', or 'step' to specify the relationship. 'Half-sister' means you share one parent; 'stepsister' means your parent married her parent and there is no blood relation.
Common Mistakes
2. a woman or girl who is not related to you by birth but who treats you with the k
a woman or girl who is not related to you by birth but who treats you with the kindness, loyalty, and emotional support expected from a family sister — a very close female friend.
Devika has been like a sister to me ever since we met in college.
'like a sister to [someone]' for a close non-relative friendship
Hana considers the four women in her book club her sisters.
When Antonia lost her job, her neighbour Marta was a true sister — cooking meals and helping with the résumé.
'a true sister' for exceptional loyalty and care
Devika's colleagues call each other sisters because their team supports one another through every challenge.
- like a sister
- sisterly bond
- sisterly love
- true sister
- sisters at heart
- close friend
neutral term for a trusted companion
- confidante
a woman you trust with secrets; more formal
- best friend
the closest level of friendship
Grammar Patterns
like a sister to [someone]
be sisters (figurative)
Usage Note
Often used figuratively in phrases like 'like a sister' or 'she is a sister to me.' This sense does not imply a blood or legal family bond. In informal Taiwan speech, terms like '好姊妹' (good sisters) or '閨密' (bestie) convey a similar meaning.
Common Mistakes
3. a fellow female activist, especially one working alongside you for women's right
a fellow female activist, especially one working alongside you for women's rights or gender equality — someone fighting the same social struggle.
Greta spoke at the conference about the bond among sisters in the global women's movement.
'sisters in [movement]' — sense of solidarity in a shared cause
The activists marched together, calling each other sisters in the fight for equal pay.
A network of sisters from across the region gathered to plan the next campaign.
At the community centre, local sisters help young women apply for college scholarships.
- sisters in the movement
- our sisters
- struggle together as sisters
- transnational sisters
Grammar Patterns
sisters in [cause/movement]
our sisters (collective address)
Usage Note
This sense carries a strong connotation of solidarity and shared political purpose. It is common in activist, feminist, and social-justice contexts. In Taiwan, similar usage appears in women's rights groups and NGO campaigns.
4. a friendly way to call out to a woman whose name you do not know, similar to say
a friendly way to call out to a woman whose name you do not know, similar to saying 'miss' in a casual setting.
'Excuse me, sister, do you know where the library is?' the young woman asked.
vocative use at the start of a question
Ari turned to the woman beside him and said, 'Sister, can you help me find platform three?'
The cashier smiled at the customer and said, 'Thank you, sister, have a great evening.'
'Don't worry, sister, I will hold the door for you,' the student called out with a smile.
Grammar Patterns
Sister, ... (at the start of a sentence)
Usage Note
Used informally, especially within African American, Caribbean, and some Asian communities as a friendly or respectful way to address a woman. In Taiwan, the equivalent '姊妹' is used in certain subcultures (e.g. church groups, online forums), but '小姐' or '美女' are more common in everyday public address.
Common Mistakes
5. a woman who commits to living in a faith-based community, taking vows of service
a woman who commits to living in a faith-based community, taking vows of service and prayer — typically referred to as a nun.
Sister Mary teaches English at the Catholic school near the old church.
title 'Sister' + first name — formal address for a nun
The sisters at the convent run a shelter for homeless families in the winter.
Christopher visited the mission and spoke with Sister Teresa about the food programme.
The sisters at the mission teach children to read and write in the after-school programme.
- Sister [First Name]
- the sisters
- convent sisters
- mission sisters
- nun
more general term; interchangeable in most contexts
- religious sister
more formal; distinguishes from a 'sister' in the family sense
- brother
male member of a religious order (e.g. Brother John)
Grammar Patterns
Sister [Name]
the sisters at [convent/mission]
Usage Note
When used as a title before a name, 'Sister' is capitalized (e.g. Sister Agnes). The term is used across Catholic, Orthodox, Anglican, and some Buddhist traditions. In Taiwan, '修女' (xiūnǚ) is the standard term for Catholic nuns.
Common Mistakes
6. a senior woman on a hospital ward who oversees patient care, manages the nursing
a senior woman on a hospital ward who oversees patient care, manages the nursing team, and reports to the doctors on the floor.
The ward sister checked each patient's chart before the doctor arrived for rounds.
'the ward sister' — specific hospital role
Ilan asked the sister on duty whether his grandmother could receive more visitors.
Sister Chen has worked as the head nurse in the emergency department for twelve years.
The night sister checks that every patient in the ward receives the correct medicine on time.
- ward sister
- theatre sister
- Sister [surname]
- sister in charge
- night sister
- charge nurse
gender-neutral modern term widely used today
- head nurse
common in US hospitals; less specific than 'ward sister'
Grammar Patterns
the ward sister
Sister [surname] (as title)
Usage Note
This sense is primarily British. In the UK, 'ward sister' or simply 'sister' is the traditional title for a senior female nurse in charge of a ward. In the US, the equivalent is 'head nurse' or 'charge nurse.' In Taiwan, the equivalent role is '護理長' (hùlǐzhǎng) or '護理督導.' This usage is becoming less common as gender-neutral terms like 'charge nurse' replace it.
Common Mistakes
7. a woman who belongs to the same college club, trade union, or professional body
a woman who belongs to the same college club, trade union, or professional body as you — your fellow member in an organisation for women.
The sorority sisters at the University of Michigan organized a charity run for cancer research.
'sorority sisters' — fellow female members of a college club
Union sisters voted together to support the new contract for fair wages.
Every new member of the association is welcomed as a sister during the induction ceremony.
The Delta Gamma sisters raised over ten thousand dollars for the local food bank.
- sorority sister
- union sister
- Theta sister
- Delta Gamma sister
- association sister
- pledge sister
- member
gender-neutral; less specific about the relationship
- fellow member
emphasizes shared membership without gender specificity
Grammar Patterns
sorority sister
union sister
[group name] sister
Usage Note
Common in American college culture, where sororities are social organizations for female students. Also used in labour unions ('union sisters') to express solidarity among female workers. In Taiwan, the closest equivalent is '學姊妹' (sister in the same school or club lineage), used in university clubs and fraternity-like organizations.
Common Mistakes
soul sister
idioma woman who shares your deepest values, feelings, or cultural background — someone you connect with on a very personal level.
When Devika met the new student from Ghana, she felt she had found a soul sister.
a humorous way to say that a woman is so close to you she feels like a sister, even though you do not share parents.
Salma calls Mira her sister from another mother because they have been best friends since nursery school.
sister — adjective
1. used before a noun to show that a business, ship, school, or other institution i
used before a noun to show that a business, ship, school, or other institution is part of the same larger group as another, normally under one parent body.
The Tokyo restaurant chain shares a delivery network with its sister company in Bangkok.
'sister company' — a company under the same parent group
Two sister ships from the same cruise line docked at the port this morning.
The Taipei office works closely with its sister branch in Kaohsiung on client projects.
Mercy Hospital is a sister institution of the medical school, sharing faculty and research resources.
- sister company
- sister ship
- sister school
- sister city
- sister branch
- sister institution
- sister organisation
- affiliated
more formal; implies a formal connection but not necessarily the same owner
- associated
general term for connected entities; broader than 'sister'
Grammar Patterns
sister [company/ship/branch/organisation]
Usage Note
This adjective is always used before a noun — you cannot say 'this company is sister.' Common word partnerships include 'sister company,' 'sister ship,' 'sister school,' 'sister organisation,' 'sister city' (a city twinned with another), and 'sister branch.' In Chinese (Taiwan), the equivalent prefix is '姊妹' (e.g. 姊妹公司, 姊妹校, 姊妹市).
Common Mistakes
Word family
- sisterlyadjectiveB2
- sisterhoodnounB2
- half-sisternounB1
- stepsisternounB1
- sisters-in-lawnounB1
- big-sisterlyadjectiveC1
Synonym discussion
Sense: noun/1
'Sister' refers specifically to a female sibling. 'Sibling' is the gender-neutral term covering both brothers and sisters — use it when gender is unknown or irrelevant. 'Half-sister' means you share only one biological parent (mother or father) with that person, while 'stepsister' means your parent married her parent and there is no blood relationship between you. 'Female sibling' is a clinical phrase rarely used in everyday speech. In informal conversation, 'sister' alone is preferred; in medical or legal forms, 'sibling' is standard. Example: 'I have two siblings — a brother and a sister' (natural distinction). 'She is my half-sister from my mother's side' (clarifies the biological relationship).
Common collocations
Nouns
- older sister
- younger sister
- little sister
- big sister
- twin sister
Phrases
- sister from another mother
- soul sister
- big sister programme
Prepositions
- sister of
- sister to
- like a sister
Etymology
The word 'sister' comes from Old English 'sweostor', which traces back to an ancient Indo-European root shared by Latin 'soror' (sister), Greek 'eōr', and Sanskrit 'svasṛ'. These all meant 'one's own female sibling.' The modern spelling 'sister' was established by the 1500s.