Deliberative describes something that exists so people can discuss, weigh, and plan before they decide. A deliberative body or deliberative assembly is a group whose job is talk-and-thought, not a snap order. A deliberative process or deliberative meeting is one designed for careful discussion. You meet it in law, government, and civic life — formal English, not kitchen English. It is cousin to deliberate in the “think it through” sense, not the “slow and unhurried” sense of a deliberate walk, though those two uses of deliberate grew from the same idea of taking time. Though actually, a deliberative group may still argue fiercely; the word names the purpose (discussion), not how gentle the room feels.