Under-carriages are a vital component of any vehicle as they support the entire weight of the automobile and ensure smooth movement. Synonyms for the term include chassis, framework, substructure, and undercar. The chassis is the frame of a vehicle that holds all the major components like the engine, suspension, and wheels. The framework refers to the structure that supports the body of the car and holds the engine, while the substructure includes all the parts that are directly attached to the chassis. Undercar is a shorthand for the under-carriage and is commonly used in the automotive industry. Regardless of the synonym, the under-carriage is an essential component of any vehicle, and proper maintenance is necessary to ensure safety and longevity.