noun

1. what a thing is made of; constituent substance or material
2. what all (material) things are made of; whatever occupies space and is perceptible to the senses in some way: in modern physics, matter and energy are regarded as equivalents, mutually convertible according to Einstein's formula, E = mc (i.e., energy equals mass multiplied by the square of the velocity of light); in dualistic thinking, matter is regarded as the opposite of mind, spirit, etc.
3. any specified sort of substance coloring matter
4. material of thought or expression; what is spoken or written, regarded as distinct from how it is spoken or written; content, as distinguished from manner, style, or form
5. an amount or quantity, usually indefinite a matter of a few days
6. 1. something that is the subject of discussion, concern, action, etc.; thing or affair business matters
   2. cause, occasion, or grounds no matter for jesting
7. the body of heroic stories and legends, as contained in a folk epic, regarded as central to a culture or literature the King Arthur stories make up the matter of Britain
8. 1. an important affair; thing of some moment or significance
   2. importance; moment; significance it's of no matter
9. an unfavorable state of affairs; trouble; difficulty: with the something seems to be the matter
10. documents, letters, etc. sent, or to be sent, by mail; mail second-class matter
11. a substance discharged by the body; specif., pus
12. Law something that is to be proved
13. Philos. that which has yet to take on form; undifferentiated substance of reality or experience
14. Printing
    1. written material prepared, or to be prepared, for printing; copy
    2. copy ready to be printed

Etymology: ME matiere < OFr < L materia, material, stuff, wood (< base of mater, mother), orig., the growing trunk of a tree

intransitive verb

1. to be of importance or consequence; have significance the things that matter to one
2. to form and discharge pus; suppurate