There are various synonyms for the phrase "is late," which means not being on time or missing an expected deadline. Some common synonyms for "is late" are behind schedule, delayed, tardy, overdue, and running late. These synonyms can be used in various contexts, such as describing a late bus, a delayed project, or a person who is running late for a meeting. Other synonyms for "is late" could include "behind time," "past due," "belated," or "not on time." No matter which synonym one chooses, the phrase indicates that something or someone has not met an expected time frame, which can cause inconvenience or frustration.