Substance, material.

A condition, subject or affair, especially one of concern.

“What's the matter?;   state matters”

An approximate amount or extent.

“I stayed for a matter of months.”

To be important.

“Sorry for pouring ketchup on your clean white shirt! - Oh, don't worry, it does not matter.”

(in negative constructions) To care about, to mind; to find important.

To form pus or matter, as an abscess; to maturate.