##### WordNet

**drag coefficient**

n. the ratio of the drag on a body moving through air to the product of the velocity and the surface area of the body [syn: coefficient of drag]

##### Wikipedia

**Drag coefficient**

In fluid dynamics, the **drag coefficient** (commonly denoted as: $\scriptstyle C_\mathrm d\,$, $\scriptstyle C_\mathrm x\,$ or $\scriptstyle C_\mathrm w\,$) is a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment, such as air or water. It is used in the drag equation in which a lower drag coefficient indicates the object will have less aerodynamic or hydrodynamic drag. The drag coefficient is always associated with a particular surface area.

The drag coefficient of any object comprises the effects of the two basic contributors to fluid dynamic drag: skin friction and form drag. The drag coefficient of a lifting airfoil or hydrofoil also includes the effects of lift-induced drag. The drag coefficient of a complete structure such as an aircraft also includes the effects of interference drag.

#### Usage examples of "drag coefficient".

He sank back and let his hands trim flaps and ailerons, clearing up the __drag coefficient__ until the plane was flying smoothly and lifting well.

The sculptured body kit improved the car's __drag coefficient__ significantly, while the lowered and stiffened suspension, allied to a set of Metzler ultra-high performance tires, gave the car superior handling and cornering capabilities.