What is matter? What is materialism?

I have often thought most philosophers vague when they talk about matter. And especially when they use the word “materialism.”And this includes some who call themselves “philosophers of science.”

And try to hunt down the definitions. Answers for example describes matter as “something that has mass and exists as a solid, liquid, gas, or plasma.” In Wikipedia we find: “Matter is the substrate from which physical existence is derived, remaining more or less constant amid changes. Anything that occupies space and has mass and weight.” Search for clarification usually produces the circular definitions that matter has substance and substances are matter.