Definitions
1.nounSubstance, material.
2.nounA condition, subject or affair, especially one of concern."What's the matter?; state matters"
3.nounAn approximate amount or extent."I stayed for a matter of months."
4.nounThe essence; the pith; the embodiment.
5.nounInducing cause or reason, especially of anything disagreeable or distressing.
6.nounPus.
7.verbTo be important."Sorry for pouring ketchup on your clean white shirt! - Oh, don't worry, it does not matter."
8.verb(in negative constructions) To care about, to mind; to find important.
9.verbTo form pus or matter, as an abscess; to maturate.