Which word means spacious or having ample space?

The word "capacious" accurately means spacious or having ample space. It is derived from the Latin word "capax," which indicates the ability to hold a large amount. In various contexts, this word conveys the idea of being able to accommodate a significant volume or number of items, making it suitable for describing anything from a room to a container.

In contrast, the other options do not convey the meaning of being spacious. For example, "fitful" refers to something that occurs intermittently or is irregular, while "prostrate" describes a position of lying flat, often due to exhaustion or submission. "Fastidious" relates to a meticulous or critical attention to detail, which does not connect to the concept of spaciousness. Thus, "capacious" stands out as the word that aligns perfectly with the meaning of spaciousness.