Matter Definition: From Atoms to What Matters

Matter definition: six senses at a glance

1. Physical substance (science). Anything that has mass and occupies space. "All matter is made of atoms."
2. A subject, issue or affair. "We discussed the matter at lunch." "Money matters."
3. Trouble or a problem. "Is something the matter with the printer?"
4. Content, as opposed to form. "subject matter," "reading matter," "printed matter."
5. A legal case. "The firm is handling the matter for the tenant."
6. Verb: to be important. "It doesn't matter." "Small details matter in cooking."

To define matter across all these: something real that you have to deal with, whether it sits on a scale or on your mind.

The definition of matter in science

In physics and chemistry, matter is any substance with mass and volume. It is built from tiny particles: atoms, which are themselves made of protons, neutrons and electrons. School science usually describes the common states of matter:

• Solid: fixed shape and volume, like ice or a stone.
• Liquid: fixed volume but takes the shape of its container, like water or oil.
• Gas: no fixed shape or volume, spreads to fill a space, like steam or air.
• Plasma: very hot, electrically charged gas, found in lightning and in stars.

Heating or cooling can change matter from one state to another without changing what it is made of. Ice, water and steam are all the same substance. Related ideas include density (mass per unit of volume), inertia and energy.

What is not matter?

Some things you can sense are not matter, because they have no mass of their own and do not fill space as substance. Light, sound, heat, magnetism, thoughts and feelings are all examples. They are either forms of energy or effects of matter moving, rather than matter itself.

Matter as an issue or problem

Outside the lab, matter usually means a subject or situation that needs attention. Common patterns:

• What's the matter? What is wrong? ("What's the matter, you look pale.")
• A matter of something: it depends on, or is about, that thing ("It's only a matter of time." "A matter of taste.")
• As a matter of fact: actually, in truth.
• No matter how / what / where: whatever the case ("No matter how late it is, call me.")
• The heart of the matter: the most important part.
• To make matters worse: adding to a bad situation.
• Grey matter: informal for brains or intelligence.

Matter as a verb

As a verb, to matter means to be important or to make a difference. It is usually used without an object: something simply matters, or does not. "Does it matter which pen I use?" "Her vote mattered." It often appears in negatives ("It doesn't matter") and with "to" ("Family matters to him").

Be careful with tone. "It doesn't matter" can sound kind ("Don't worry about it") or dismissive ("I don't care"), depending on how it is said.

Matter in sentences

• The rings of some planets are made of ice and rock, which counts as matter.
• The principal said the matter would be settled after the holidays.
• "What's the matter with your phone?" "The screen keeps freezing."
• No matter what you choose, I'll support you.
• To make matters worse, the bus broke down in the rain.
• Whether you finish first or last doesn't matter; just finish.

Origin and related words

Matter came into Middle English through Old French matere from Latin materia, which meant the stuff a thing is made from, and also the hard inner wood of a tree. From "what something is made of," the sense widened to "what a speech or book is about" and then to "an affair or concern." The verb sense of being important developed later, in the sixteenth century.

Close relatives include material (the stuff a thing is made from, or relevant in a legal sense) and materialize (to appear or become real). For more useful everyday terms, try the everyday vocabulary hub or the science and ideas list.