Like volume measures

CUBIC

["Think of how we describe the space inside a box or the units used for three-dimensional shapes like a die."]

The clue "Like volume measures" hints at units used for three-dimensional space, such as cubic inches or cubic meters. "Cubic" directly describes these measurements, as volume is calculated in cubes (length × width × height). The wordplay is straightforward—no tricks—just a direct reference to how we quantify space.