When a person unlawfully fights in a public place or willfully and maliciously disturbs another person by loud and unreasonable noise, s/he is said to be committing breach of peace. It is breach of peace to say offensive words to one or more persons that are likely to start an immediate violent reaction in a public place.
The following is an example of a case law defining the term:
The term "breach of the peace" can be defined as "to agitate, to arouse from a state of repose, to molest, to interrupt, to hinder, to disquiet." Cox v. La., 379 U.S. 536, 551 (U.S. 1965)