The term 'OPEN A COMPRESSED FILE' can be solved by the crossword solution 'UNZIP', which is a five-letter word. Unzipping is a process of decompressing a file that has been compressed, usually to reduce its size. This process is often used to transfer files over the internet, as it reduces the amount of time and data needed to send the file. Once the file is unzipped, it can be opened and used as normal.