What is the definition of matter?

The definition of matter is accurately captured as anything that has mass and occupies space. This encompasses a broad range of physical substances, including solids, liquids, and gases. All forms of matter are characterized by having weight due to mass and the ability to take up a certain volume in three-dimensional space.

The understanding of matter is fundamental to various scientific disciplines, including physics and chemistry, where the interactions and properties of matter are explored. This definition distinguishes matter from energy, which does not have mass or occupy space in the same manner as matter does.

In contrast, the other options focus on more specific aspects or concepts that do not encompass the entire definition of matter. For example, a substance having a fixed shape is not applicable to all matter, especially liquids and gases that can change shape. Describing matter as a form of energy is misleading, as energy is a different concept entirely and does not possess mass. Lastly, classifying chemical compounds does not capture the broader definition of matter since not all matter is a chemical compound; it includes elements and mixtures as well. Therefore, the most comprehensive and accurate definition of matter is indeed that it is anything that has mass and takes up space.