(physics) is commonly defined as the substance of which physical objects are composed.
To be important.
A vaguely specified subject, question, situation, etc. that is or may be an object of consideration or action.
have weight; have import, carry weight; "It does not matter much"
(used with negation) having consequence; "they were friends and it was no matter who won the games"
a problem; "is anything the matter?"
a vaguely specified concern; "several matters to attend to"; "it is none of your affair"; "things are going well"
written material (especially in books or magazines); "he always took some reading matter with him on the plane"
that which has mass and occupies space; "an atom is the smallest indivisible unit of matter"
some situation or event that is thought about; "he kept drifting off the topic"; "he had been thinking about the subject for several years"; "it is a matter for the police"
written works (especially in books or magazines); "he always took some reading matter with him on the plane"
