Thank you KRUDALA and โอ๋-อโณ : I have hope that someone 'out there' may give me more clues or a right direction for both the etymology of มวล and how to fix the problems of 'road litter'. (The current prime minister of Thailand had shown his preference to burn litter to generate electricity to supply the power grid authority at a fixed and profitable price by law. Will this also solve 'road litter' problems? We should ask ...)