Gray Rock
Gray rock is a way of responding to a manipulative or high-conflict person by becoming as boring and unreactive as a plain stone, giving short, flat answers and no emotional fuel for them to feed on.
Some people are energized by your reaction. Upset, defense, even tears can read to them as a win, a sign they still have a hold on you. Gray rock is a response to that: you keep your answers brief and uninteresting, you stop offering the details and the feelings that give them something to grab, and you let yourself go dull on purpose.
It is a coping move for situations you cannot fully leave, a coparent, a relative at a holiday, a colleague you are stuck near. The aim is not to win or to change them. It is to lower your exposure and stop being a reliable source of the drama they are looking for. Over time, with less to react to, many lose interest and drift toward an easier target.
It has limits worth knowing. Going flat costs energy and can feel lonely and false, and some people escalate when they sense they are being managed. Gray rock is a shield for a hard stretch, not a way to live, and it pairs best with as much distance as the situation allows.