The term 'stir turbulently' can be summarized by the crossword solution 'ROIL, ' which is a four-letter word. ROIL means to cause something to become agitated or disturbed, often in a turbulent manner. It is derived from the Middle English word 'royllen, ' which means to boil or bubble. Roiling is often used to describe the motion of water, such as when a river is roiling with rapids or when a lake is roiling with waves.