noun, plural: matters
(1) The material of the universe, especially one that occupies space and has mass
(2) The substance that make up an object
In general science contexts, the term matter refers to anything (a substance or a material) from which objects are made. Generally, matter is made up of atoms, has (rest) mass, and occupies space (volume). There are basically four phases or states of matter: (1) solid, (2) liquid, (3) gas, and (4) plasma. A solid matter is characterized by its definite shape and volume. The molecules that make up a solid matter are closely and tightly packed thus giving it a particular shape. A liquid matter is characterized by its lack of a definite shape but with a definite volume. The molecules that make up a liquid matter are tiny vibrating particles that take up the shape of its container. Water is the most common form of a liquid on earth. Liquids flow and most of them resist compression. Gas is a matter that is made up of molecules that are distant from each other, thus, it does not have a fixed shape and most gases are not visible to its observer. Plasma is an ionized state of matter. It is made up of partially ionized gas.