thermostat: A device that keeps the hot coolant confined to the engine cooling passages to help the engine warm up more quickly. After the engine has warmed up, the thermostat allows the coolant to flow to the radiator, where it’s cooled and recirculated through the engine to prevent overheating.

throw-out bearing; clutch release bearing: A part of the clutch, activated by the clutch pedal, that allows the clutch to disengage. If you allow the car to idle in gear with the clutch pedal pressed instead of shifting to Neutral, you can wear out the throw-out bearing.

transmission fluid: A thin oil that fills the automatic transmission so that it can run on hydraulic pressure. It’s also found in many power-steering pumps.

tune-up: The process of replacing a vehickle's fuel filters, air filters, and spark plugs to ensure that air, fuel, and spark are available in good condition to obtain maximum engine efficiency.