The phrase "busy work" refers to a task that is mindless and unproductive but keeps one busy. There are several synonyms for the word "busy work" that can be used to describe the same thing, such as grunt work, make-work, meaningless work, tedious tasks, pointless tasks, or time-wasting tasks. These synonyms are often used in a negative context to describe work that is repetitive and lacks any significant value or purpose. However, it's essential to note that sometimes busy work can be necessary to complete more complicated jobs, but individuals should always strive to find meaning and purpose in their work when possible.