The term 'SPACECRAFT UNIT' can be broken down into two parts: 'SPACECRAFT' and 'UNIT'. The word 'SPACECRAFT' is defined as a vehicle designed to travel in outer space, while the word 'UNIT' is defined as a single thing or person. The crossword solution for this term is 'MODULE', which is a self-contained component of a SPACECRAFT that performs a specific function. It is typically composed of multiple parts and is designed to be easily removed and replaced. Modules are often used to provide power, propulsion, navigation, communication, and other necessary functions for a SPACECRAFT.