| an extraordinary or unusual thing, person, or event; an exceptional example or instance. |
| a calculus or concretion found in the stomach or intestines of certain animals, esp. ruminants, formerly reputed to be an effective remedy for poison. |
| turbulence (tûr'byə-ləns) Pronunciation Key
Chaotic or unstable eddying motion in a fluid. Avoiding excessive turbulence generated around moving objects (such as airplanes), which can make their motion inefficient and difficult to control, is a major factor in aerodynamic design. |