noun

each of a pair of marks ( ) [ ] { } 〈 〉 used to enclose words or figures so as to separate them from the context.

symbols are given in brackets

parenthesis,brace,round bracket,square bracket,angle bracket,curly bracket

verb

enclose (words or figures) in brackets.

I have bracketed the phrase ‘of contrary qualities’ in the translation, since it is not explicit in the Greek