What defines matter best?

Defining matter as anything that has mass and occupies space provides a comprehensive understanding of what constitutes matter in the physical sciences. This definition captures both essential characteristics: mass, which indicates the amount of substance in an object, and volume, which refers to the space that the substance occupies.

In scientific terms, all physical objects that can be perceived, measured, or interacted with in the universe are made of matter, and this matter is tangible in the sense that it has both weight and takes up space. Therefore, this definition accommodates a wide range of materials, from gases like air to solids like rocks, thereby encompassing all states of matter.

The other options fall short in different ways. For example, defining matter merely as anything with defined dimensions is too narrow since substances can have irregular shapes and sizes. Describing matter as anything invisible misrepresents the concept—many forms of matter are visible and can be observed directly. Lastly, stating matter is anything that occupies space does not include the mass aspect, which is crucial for a complete understanding of what matter is. Hence, the most accurate and inclusive definition of matter is that it is anything that has mass and occupies space.