When a potentially violent situation becomes less intense, reducing the likelihood of a conflict, that's de-escalation. Instead of another loud argument with your brother, you might aim for de-escalation.
De-escalation is a technique that's used by a wide variety of people, from police officers to company managers to elementary school teachers to leaders of countries. Turning down the intensity of a disagreement, ideally getting people to discuss their issues instead of shoving each other (or starting a war) is what de-escalation is all about. The word comes from the prefix de-, "the opposite of," and escalate, or "raise," from a Latin root meaning "to climb."