Turbulence is air that will not stay smooth. The plane drops half a metre, the coffee jumps in the cup, the seatbelt sign pings on and the cabin crew go back to their seats.
Turbulence belongs to water as much as to air: the churning behind a boat, the white mess where a river hits rocks. Engineers use it for a real state of a moving fluid, turbulent flow, where the movement breaks into swirls and eddies instead of running in neat parallel lines. Away from planes and rivers it means a stretch of trouble and instability: political turbulence, turbulence in the markets, a turbulent decade. It is uncountable, so you hit turbulence, never a turbulence. The adjective is turbulent, and it goes with times, years, relationships and waters.
1nounturbulenceViolent, uneven movement of air that shakes an aircraft in flight.
“We hit turbulence over the Alps and the drinks trolley was put away.”
2nounirregularIrregular, swirling movement in air or water, as opposed to smooth steady flow.
“The wing tips leave turbulence behind them that smaller aircraft have to keep clear of.”
3nounupheavalA stretch of confusion and instability in a life, a country or a market.
“The company came through a decade of turbulence with half the staff it started with.”
turbulence is a rough, unsteady kind of movement.
In Middle English, turbulence meant cloudiness: water with the mud stirred up through it. It came from Latin turbulentia, which meant trouble and disquiet, the stirred-up state of a mind or a crowd rather than of a liquid. That older sense is still there in turbulent times. The muddy water came first; the shaking plane came a long way after.
Latin
turbulentia — trouble, disquiet
Middle English
turbulence — turbidity, cloudiness
English, today
turbulence
From Middle English turbulence (“turbidity, cloudiness”), from Latin turbulentia (“trouble, disquiet”). by surface analysis, turbulent + -ence.
Etymology from Wiktionary, CC BY-SA