Dimensional means relating to dimensions, which are measurements of space. When we describe something as three-dimensional (or 3D), we mean it has length, width, and height, like a soccer ball or a building. A flat drawing on paper is two-dimensional (2D) because it only has length and width, no depth.

Scientists and mathematicians use the word dimensional when discussing how many directions you can measure something in. A line is one-dimensional because you can only measure along its length. A square is two-dimensional. A cube is three-dimensional. Some theoretical physicists even explore the possibility of additional dimensions beyond the three we experience every day, though these remain invisible to us.

You might also hear dimensional in everyday contexts. Someone might describe a character in a story as multi-dimensional when they seem realistic and complex, with different sides to their personality. A one-dimensional character, by contrast, feels flat and boring, like a cardboard cutout with only a single trait.

The word can even apply to problems. A multi-dimensional problem has many different aspects that all need attention, like planning a class field trip where you have to consider transportation, cost, time, safety, and what everyone will learn.