volatile

Universal Words adjective 1 (often disapproving) (of a person or their moods) changing easily from one mood to another: a highly volatile personality 2 (of a situation) likely to change suddenly; easily becoming dangerous: a highly volatile situation from which riots might develop * a volatile exchange rate 3 (technical) (of a substance) that changes quickly into a gas: Petrol is a volatile substance. volatility noun [U]