Learn English – Brackets Vs Parenthesis

american-englishbritish-englishprogrammingterminology

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?

Best Answer

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.

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