Bywork is a term that is not widely used in the English language anymore. It refers to secondary or additional tasks that are done in addition to one's primary responsibilities. If you are looking for synonyms for bywork, consider using terms such as sideline, side gig, side job, secondary task, additional job or additional task. These synonyms convey the same meaning as bywork and are commonly used in modern English. In today's fast-paced and ever-changing work environment, it is important to be flexible and open to taking up additional tasks to stay competitive and add value to your organization while pursuing your primary responsibilities.