I came across this question on Meta Stackoverflow, where a discussion was going on in the comments about the terms brackets and parenthesis and the right usage of them.

It seems there is a different usage in British English and American English. Because I’m German I didn't have a clue about this and would like to know if there really is a difference.

The Oxford Dictionary denotes brackets as: ( ) and [ ], but I think { } and < > belong to this family too, where for example { } are curly-brackets.

Parenthesis is the term only for ( ).

Is this true for both British and American English? If not, where is the exact difference?

  • 1
    In American technical (linguistics, CS) usage, [square brackets], {curly brackets}, and <angle brackets> are varieties of bracket; (parentheses) function the same way, but use a different name. All are used for bracketing (or bracketting), though the verb to bracket has several other uses that don't involve punctuation. – John Lawler May 7 '14 at 17:43
  • @JohnLawler This is the way I'm familiar with. Thanks for pointing this out and for the sheet! – Steve Benett May 7 '14 at 18:12
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    Steve Benett, I suspect that the word "parentheses" is part of American English in particular. I have not seen or heard it used in the UK. – Tristan r May 7 '14 at 22:31
  • The problem that parenthesis means "putting in between", and as such it is often used to describe the phenomenon, instead of certain marks that are often used to effect parenthesis in writing, like ( ). Cf. the adjective parenthetical. To use parenthesis for both the phenomenon and a particular kind of bracket is confusing and, I should say, infelicitous. We have the word bracket, which is a perfectly nice and clear word. Brackets or round brackets is what I would call ( ), and they can be used to designate parenthesis, as can commas , ,, dashes — —, etc. – Cerberus May 8 '14 at 4:14
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In U.S. publishing, the most common terms for these punctuation marks are as follows:

( ) parentheses or parens

[ ] brackets or square brackets

{ } braces or curly brackets or set symbols

< > angle brackets

In some math textbooks, you may also encounter these two types of brackets:

⌊ ⌋ floor brackets

⌈ ⌉ ceiling brackets

RapidTables has a page devoted to numerous mathematical symbols, including various types of brackets. I believe that the terminology reported there reflects U.S. naming conventions.


Correction: In a comment below, I inadvertently misstated RapidTables' description of the function of the ⌊ ⌋ and ⌈ ⌉ brackets as "rounding down" and "rounding up"; the wording that RapidTables actually uses is "rounds number to lower integer" and "rounds number to upper integer." However, tchrist (who clearly has a better grasp of the situation than I do) says in a comment below that the words "rounding up" and "rounding down" misrepresent what floor and ceiling functions do. I reproduce part of his comment here, for accuracy: "The floor and ceiling functions are not “rounding down” or “rounding up”. floor(-4.3) or ⌊ −4.3 ⌋ = −5, while ceiling(-4.3) or ⌈ −4.3 ⌉ = −4. So floor(𝑛) rounds to the largest integral value not greater than 𝑛, while ceiling(𝑛) rounds to the smallest integral value not less than 𝑛." Thanks, tchrist!


Words Into Type, Third Edition (1974) indicates that, in U.S. publishing 40 years ago, compositors used the term bracket very narrowly:

[Footnote 36] The terms curves and round brackets are never used in [U.S.] composing rooms for parentheses. The term there used is parens, separately designated open paren and close paren.

[Footnote 37] The word bracket signifies only one thing to a compositor. Asking him to use a "square" bracket is unnecessary.

The terms open paren and close paren remain common in U.S. publishing today. In view of the rise of angle brackets (especially in computer coding) and the expanded use of curly brackets, however, I doubt that any surviving compositor would deem the term square bracket redundant.

  • Thanks for the confirmation, that's the terms I'm used to. – Steve Benett May 7 '14 at 18:23
  • 'Floor brackets' and 'ceiling brackets' are new to me. I suspect they have well-defined usages. – Edwin Ashworth May 7 '14 at 18:37
  • @EdwinAshworth The RapidTables site says that they indicate "rounding down" and "rounding up," respectively: ⌊4.3⌋= 4 but ⌈4.3⌉= 5. I doubt that the need for them arises very often. – Sven Yargs May 7 '14 at 18:47
  • Thank you, Sven. In my day, square brackets were used (at least in our neck of the woods) for the round-down function. – Edwin Ashworth May 7 '14 at 21:57
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    @EdwinAshworth The floor and ceiling functions are not “rounding down” or “rounding up”. floor(-4.3) or ⌊ −4.3 ⌋ = −5, while ceiling(-4.3) or ⌈ −4.3 ⌉ = −4. So floor(𝑛) rounds to the largest integral value not greater than 𝑛, while ceiling(𝑛) rounds to the smallest integral value not less than 𝑛. This is not rounding up or down. It is something else altogether, and is much better defined. If you want rounding towards zero, use integer truncation. – tchrist May 8 '14 at 4:32

In ordinary British English, brackets denotes '()': they may also be called parentheses, but that is a formal word. '[]' and '{}' are square brackets and curly brackets (or braces) - loosely, they may all be called brackets, but as I say, the word usually means the curved ones. I would not think of '<>' as any kind of bracket: until computer programming, I don't believe they were ever used as delimiters in that way.

As you say, American usage seems to be different.

  • If you say the word bracket may be used to call these punctuations as a genus, is there also a different term for these? – Steve Benett May 7 '14 at 18:22
  • It's not just formal, it's very rare. I haven't heard the word "parentheses" used in the UK. – Tristan r May 7 '14 at 22:28
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    Inequality signs (<>) were probably not used for bracketing before computer programming; but the similar single guillemets (‹›) and chevrons (〈〉) have been in use much longer, just not very commonly in English: single guillemets function as single quotation marks in the many languages that use guillemets as the default (or possible) quotation marks, most notably French (not technically bracketing as such); while chevrons are used within the field of linguistics to mark graphemes (actual bracketing), as well as having various meanings in maths, physics, and other areas. – Janus Bahs Jacquet May 7 '14 at 22:53

If you are talking about common general usage and not someone who works in publishing, programming or mathematics, then this is the basic difference:

Symbol     American English                British English
------     ----------------                ---------------
()         parentheses                     brackets *or* round brackets
[]         brackets *or* square brackets   square brackets

The confusion is because "brackets" mean () in the US and [] in the UK. So it's better to be clear and say "square brackets" when you mean the square kind.

However, if you want the round kind, the term "round brackets" is not commonly used in the US (again, by "normal people" who don't work in a specialized industry) and the common person would not know what you mean by this. "Parentheses" would be the common name in the US.

  • Your first sentence has accidentally swapped symbol pairs. – philipxy Aug 29 '17 at 21:10

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