The term ALARM CAR is composed of two words, HORN and CAR. The word HORN is a four-letter word that refers to a device used to make a loud sound as a warning or signal. It is usually made of metal and is found on vehicles such as cars, trucks, and buses. The word CAR is a three-letter word that refers to a motor vehicle with four wheels, typically used for personal transportation. Together, the two words form the term ALARM CAR, which is a vehicle equipped with an alarm system that is activated when the vehicle is tampered with or moved without permission.