Turbulence is a state of extreme motion resulting in uncontrollable movement.
In 2268, after the USS Enterprise lost contact with the USS Intrepid and was out of communication with the entire Gamma 7A solar system, deflector shields snapped on due to indications of energy turbulence ahead. The probing of the dark zone phenomenon caused further turbulence when an unknown boundary layer was penetrated and they entered a zone of energy. It was later determined that the cases of turbulence were the reflexes of the space amoeba being stung by their probes. (TOS: "The Immunity Syndrome")
When the Ares IV orbiter was intercepted by a graviton ellipse, the orbiter encountered extreme turbulence, in which it was thought to have been hit by a solar flare. (VOY: "One Small Step")
In 2372, Tom Paris was able to generate a dielectric field with a Class 2 shuttle's warp coils in order to avoid extreme turbulence on a Drayan moon, which sent Lieutenant Tuvok's shuttle crashing down to the surface. (VOY: "Innocence")
In 2375. Captain Kathryn Janeway went to sickbay with symptoms of nausea and dizziness which The Doctor diagnosed as a simple case of space sickness, the third that he had treated that day. Janeway considered that odd as they hadn't run into any turbulence. The Doctor suggested that inertial dampers could be out of alignment. While she would check the dampers, Janeway told The Doctor to double-check his bioreadings to see if there was another explanation. (VOY: "Relativity")
In the first draft script of ENT: "Fusion" (which had the working title "Equilibrium"), just before heading into the Arachnid Nebula, Enterprise NX-01 detected, in Malcolm Reed's words, "a few pockets of turbulence" (as well as gravimetric shear) ahead of the ship.