There are numerous synonyms that can be used to express the concept of "passing time". One of the most common terms is "kill time", which refers to an activity that one engages in to make the time pass more quickly. Other common expressions include "waste time", "spend time", "while away time", and "occupy time". Furthermore, some people use "fritter away" to describe an activity that is not productive and only serves to fill time. On the other hand, "make the most of time", "utilize time", and "maximize time" all imply that time is a valuable resource that should not be squandered. Ultimately, the choice of synonym depends on the context and the connotations one wishes to convey.