`sibling' meaning in Cambridge dictionary

sibling noun [ C ]
a brother or sister:
I have four siblings: three brothers and a sister.

My understanding of the word was that it meant only children of the same parents. My question is:-

  1. Can we use it instead of a brother or sister in these situations :-
    a) a step brother one hasn't met?
    b) a child, one's parents have adopted.
  2. How would one differentiate a step brother by using the word 'sibling'?
    Please explain the usage of the word?

Edit 1.
As per my Oxford Advanced Learner's dictionary - sibling meaning is 1 line and 'brother' is more than a quarter page.

sibling: each of two or more people with the same parents; a brother or sister

The term "brother" (more than a quarter page) has a broader definition and can have multiple connotations.

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5 Answers 5


There is no difference between the usage of "sibling" and the usage of "brother" or "sister" except that it's gender-neutral. Your stepbrother is your stepsibling, and your adopted brother is your adopted sibling. In edge cases like these, where someone is "kind of" your brother, he is equally "kind of" your sibling and requires the same qualifiers.

  • 11
    @MichaelHarvey I think you are right. The main difference between half-siblings and step-siblings is their biological connection to you. Half siblings share a blood relation, while step-siblings do not Commented Jun 24 at 7:21
  • 7
    One thing I would add to this (for completeness) is that sibling is not used in the sense of comrade, as brother and sister are. Apart from that there is no difference, as you say. Commented Jun 24 at 11:21
  • 8
    @NoName - I don't know that it's because of transphobia, but rather perhaps more because the metaphorical meanings of "brother" and "sister" had centuries to develop, whereas "sibling" was reintroduced to English barely more than a century ago after a good half-millenium of disuse, taking a bit longer to make the jump from academic to colloquial English, and thus did not have as much time to accrete that secondary meaning. That said, yes, obviously, "sibling" should be used in any context in which "brother" or "sister" would be appropriate, including metaphorical ones.
    – Obie 2.0
    Commented Jun 25 at 8:34
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    I disagree that "edge cases" require a qualifier; as Chris Sunami says, relationships are a cultural construct, and many families would utterly reject the idea that they should always label themselves differently because they have adopted, or re-married, or any of the many other reasons they might not form a perfect genetic tree. The qualifiers exist if and when they are relevant or desired, but it would be perfectly valid for someone to say "I have two siblings, one of whom is a full sibling".
    – IMSoP
    Commented Jun 25 at 11:31
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    @IMSoP I completely agree and I don't think I implied otherwise. Sibling requires the same qualifiers as brother or sister, which is to say it may or may not require them depending on the nature and character of the relationship and the context in which it's being discussed. Commented Jun 25 at 12:35

The distinction is not as much in terms of dictionary definition, but more a matter of individual and cultural preference. Technically "sibling" means "brother or sister," it feels slightly more formal than either, and it's used in situations where the gender of the sibling is not specified, or it's a mixed gender group (or, in the modern context, where the sibling is nonbinary).

Many people view an adopted or step-sibling in the same light as a blood relative, and refer to them in the same way, using the same terms. Others would never do so. This varies by subculture, individual preference, parental fiat, and also, the age of the children when they became part of the same family.

Generally, any time a given person would say "brother" or "sister," it can be replaced by "sibling." The exception is when someone is using "brother" or "sister" more metaphorically, to talk about people who are not relatives at all ("brother in Christ," "the sisters on the corner," "all men are brothers").

  • 7
    I feel like someone could say "siblings in Christ" and "all humans are siblings" and be easily understood without sounding like an alien. I don't think the metaphorical usage is such a stretch. Though if someone said "the sisters on the corner" to mean "the women on the corner" (or "the Black women on the corner"), I definitely think someone would have to be very dedicated to making a specific point about gender neutrality or non-binary inclusion to say "the siblings on the corner," and I think they would be all but guaranteed to be misunderstood as referring to a familial relation.
    – Obie 2.0
    Commented Jun 25 at 8:47
  • 1
    The second paragraph here is spot on. Generally, we don't go around enquiring about the genetic relationships between people, we talk about the cultural relationships, and "sibling" can be used in a wide range of families. "Step-sibling", "half sibling", etc are all possible if someone wants to be specific, but so is the contrasting "birth sibling" or "blood sibling" (with the caveat that "blood brother" is also used to refer to something different).
    – IMSoP
    Commented Jun 25 at 11:20
  • 1
    This is a good answer. I would say I have four siblings: two full and two half. Commented Jun 25 at 12:52
  • I like your explanation - Many people view an adopted or step-sibling in the same light as a blood relative, and refer to them in the same way, using the same terms. Others would never do so. I found that some cultures following polygamy do not consider their "half brothers" as siblings. Commented Jun 26 at 9:53

As other answers explain, 'sibling' is simply a general, gender-neutral term for 'brother' or 'sister'.

There is also a non-biological usage that you might encounter in technical contexts. When we talk about relationships using graph theory, terms like 'parent', 'child', and 'sibling' are often used. Non-gendered terms are typically used for such relationships.


It seems to me that you have already answered it yourself. The dictionary does NOT say genetic brother or sister. It is normally used when one doesn't know the mix of brothers and sisters. Now, it is probably PC to make things genderless.

In your examples, you can use the word "sibling".


"Sibling" is just a general term for describing brothers and sisters in one family but if you bring like a stepbrother or stepsister into the family technically they are part of your family and you can safely call them "siblings". Also applies with adopted brothers/sisters. The dictionary says the definition of a sibling is : "each of two or more children or offspring having one or both parents in common; a brother or sister" the parents in common (whether biological or "adoption" parents) affects if they're called "siblings" or not.

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    While this answer is correct, it doesn't seem to add anything that earlier answers haven't already discussed. Also, you mention a dictionary definition, but don't specify which dictionary: it would be helpful if you could edit your answer to provide a link. Commented Jun 25 at 17:10

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