Word forms: plural parentheses (pərenθəsiːz)1. countable noun [usually plural]Parentheses are a pair of curved marks that you put around words or numbers to indicate that they are additional, separate, or less important. (This sentence is in parentheses.)
2. countable nounA parenthesis is a remark that is made in the middle of a piece of speech or writing, and which gives a little more information about the subject being discussed.