roil

Roil is a verb that means to disturb or agitate a liquid by stirring or mixing, causing it to churn, foam, or become cloudy. The action is typically intentional and produces visible movement on the surface of the liquid. It is commonly applied to liquids such as water, oil, ink, or soup, but can also describe a moving mass of material in a container.

In addition to the literal sense, roil is used figuratively to describe stirring up people, opinions, or events. For example, a provocative remark can roil a crowd or roil public sentiment, turning a calm discussion into a heated debate. The word appears in the forms roiled (past tense) and roiling (present participle), and it can describe both physical agitation and social or emotional disturbance.

Etymology and usage notes: roil appears in Middle English as roilen or related forms, with the sense tied to stirring or rolling motion. The exact origins are not entirely clear, but the term is closely linked to the idea of vigorous mixing. Roil is more precise than plain stir or churn and is often chosen to emphasize turbulence, cloudiness, or disturbance. It is related, though not identical, to rile, which primarily conveys irritation or provocation rather than physical agitation.