Are these words interchangeable? I'm especially interested in how formal/informal are they. Is there any difference between American and British usage?

The discussion on english-test.net where two native speakers argue about the word sibling inspired me to ask this question.


3 Answers 3


Sibling is more often used in American English when just referring to how many brothers and sisters a person has. Like "I have 5 siblings" or "Kelly has no siblings". This is more used on like surveys or questionnaires.. for whatever reasons.

In informal conversation, a sibling is used as a way to ask a person a question like "How many siblings do you have?" or "Do you have any siblings?". This is most often the sort of question that would be asked to get to know someone better. So with this type of question, the person normally would expect the answerer, to state how many are brothers and how many our sisters in their answer, not just the count of siblings. Like "I have 2 brothers and 3 sisters. Brothers are teenagers, one sister is graduated from college, and the other two sisters are in junior high school."


I'm American, so this is my personal usage and undertanding. I use siblings if I’m unsure of gender, and want to use a shorter construction than ‘brothers and/or sisters’. If I know someone only has brothers, or only has sisters, I probably wouldn’t bother with siblings: I’d simply say brothers or sisters. I use siblings less often than brother and sister, but I do use it.

Basically, sibling is used when brevity is more important than specificity, or where you actively don’t want to mention genders.

As A E mentioned, with a young child, I’d use brother/sister regardless, but mostly because I wouldn’t expect them to know the word sibling yet.


American English uses 'sibling' more often because of its large Germanic population. (In German, the term 'Geschwister' (siblings) is totally normal, and no-one breaks it down into 'brothers and sisters').

On the other side of the Atlantic, it is considered a formal word, and those with a restricted vocabulary wouldn't even know it. (If you worked in an underprivileged area, you wouldn't use it when speaking to parents).

It is not a word we would use in casual conversation, and has, to me, an element of psychological analysis.

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