To alternately ebb and flow.

The flowing out and in of the tide. / (figuratively) A large flowing out and in.

(volcanology) A dense flow of volcanic ash, dust, rocks and debris that cascades at high speed down the slope of a volcano during an eruption.

(thermodynamics) An idealised fluid flow in which entropy remains constant throughout the flow, or along a particular streamline.

(physics) A form of irregular viscous flow in which the velocity and pressure of the fluid fluctuates at random in both time and space,

Alternative spelling of airflow

(physics) Any fluid flow in which movement is proportional to the applied force (above the yield value). / (geology) Any deformation caused by a sustained force.

(physics) A smooth, streamline type of viscous flow in which the fluid behaves as a system of orderly layers, with no eddies or irregular fluctuations.

(accounting) The sum of cash revenues and expenditures over a period of time. / (accounting) A statement of such transactions.

(physics) A form of electrochemical storage cell in which electrolyte flows between connected tanks; the direction of flow being opposite when the cell is charging and discharging; used to store electricity from intermittent suppliers such as wind farms.