Tic
A tic is a sudden, repetitive, nonrhythmic motor movement or vocalization involving discrete muscle groups. Tics can be invisible to the observer, such as abdominal tensing or toe crunching. Common motor and phonic tics are, respectively, eye blinking and throat clearing.
Idle air control actuator
The IAC actuator is an electrically controlled device, which gets its input from the vehicle's engine control unit (ECU). The actuator is fitted such that it either bypasses the throttle or operates the throttle butterfly valve directly. The actuator consists of a linear servo actuator servomotor that controls a plunger which varies air flow through the throttle body. The position of the servomotor and hence the amount of air bypass is controlled digitally by the engine ECU. This allows the engine's idle speed to be maintained constant. The linear servo is most commonly a combination of a DC motor, lead screw and a digital optical encoder.