According to this dictionary
definition 2 of "break off" is:
to stop or end suddenly or cause (something) to stop or end suddenly
definition 1b of "break up" is:
to end or cause (something) to end
which suggests that "break off" = "break up".
So, does it mean the a-sentence and b-sentence in the following pairs:
1a "Police broke off the fight."
1b "Police broke up the fight."2a "The two countries have broken off diplomatic relations."
2b "The two countries have broken up diplomatic relations."3a "The negotiations resumed soon after they were broken off."
3b "The negotiations resumed soon after they were broken up."
are the same?
Best Answer
There is an important difference not explicitly mentioned in those definitions: the grammatical subject of break off refers to a different agent than the grammatical subject of break up.
The subject of break off was previously participating in or causing the activity that ended. The activity ended because the subject stopped continuing it.
The subject of break up was outside the activity, not part of it.* The subject actively interfered with its continuation, causing it to stop.
For example:
means that some people, not the police, were fighting, and the police forcibly made them stop fighting. Most likely, the police physically grabbed the combatants, pulled them apart, and restrained them.
means that the police were themselves involved in the fight, and stopped fighting by their own choice. Perhaps the police were defending a building against a crowd during a public protest, and the police lost heart and decided to walk away and let the crowd do as it pleased. Or perhaps the "fight" was a negotiation to get a raise in pay. Then if the police "broke off" this fight, that would mean that they gave up trying to get the raise, agreeing to continue to work at their present salary.
When people "break off negotiations", this means that they refuse to continue negotiating. They have given up hope of making a deal, or they demand a concession from the other side before they will even continue talking. They have "walked away from the negotiation table."
*Of course, there is also a different sense of break up, such as sense 2, the break-up of a romantic relationship, in which the participants do end it.