When trying to describe a task or event that lasts all day, it's important to have a variety of descriptive words at your disposal. Some synonyms for all-day include full-day, entire day, 24-hour, non-stop, perpetual, and continuous. These words can help to paint a more accurate picture of what is being described, and also lend a sense of urgency or intensity to the description. Whether you're talking about a marathon, a work project, or a fun day out, having a rich vocabulary to draw from can elevate your writing and make your descriptions more engaging.