The word "hollows" is often used to describe empty or empty spaces. However, there are many other synonyms that can be used to convey the same meaning. Examples include cavities, depressions, concavities, dents, craters, trenches, dips, valleys, and sinkholes. Each of these words can be used to describe a different type of hollow or empty space, depending on the context in which they are used. Whether writing about a cave system, a canyon, or a decayed tree trunk, it is important to choose the most appropriate synonym to accurately convey the intended meaning.