Undertime is a term used to describe the opposite of overtime. It refers to hours worked that are less than the required or expected schedule. There are several synonyms for undertime, including reduced hours, short time, part-time, or abbreviated workday. Other words that can be used to describe undertime include curtailed, abbreviated, truncated, or abridged. In certain industries, undertime may be called slack time, downtime, or idle time. It is important to note that while undertime is often viewed negatively, it may be a necessary part of a flexible and accommodating work schedule.