Definitions for understeerˈʌn dərˌstɪər; ˌʌn dərˈstɪər
Random House Webster's College Dictionary
un•der•steerˈʌn dərˌstɪər; ˌʌn dərˈstɪər(n.; v.)
a tendency of an automobile to turn less sharply than the driver intends.
(v.i.)to exhibit understeer.
Ref: Compare oversteer.
The condition in which the front wheels of a car don't follow the desired curve while cornering, instead following a more straight line trajectory. The front wheels loosing a degree of traction and so slipping off the required line.
The action of a car when it does not follow the desired curve while cornering. Tyre slip of the front wheels.