The term 'Piece of Work to be Done' can be summarized as a TASK that needs to be completed. It is usually used to refer to a job or project that requires effort and dedication in order to be finished. The four-letter solution for this term is 'TASK'. This term is often used in the workplace, where it is used to refer to a specific job or assignment that needs to be done. It can also be used in other contexts, such as when referring to a TASK that needs to be completed in order to achieve a certain goal.