What is another word for groundmass?
Pronunciation: [ɡɹˈa͡ʊndmas] (IPA) 
Groundmass refers to the fine-grained matrix in which larger crystals or minerals are embedded in igneous rocks. Synonyms for groundmass include the terms base, matrix, and paste. The base refers to the groundwork on which a structure is built, similar to how the groundmass forms the background for larger crystals in a rock. The matrix is a surrounding substance in which something develops or is embedded, just as the groundmass surrounds and embeds larger minerals. The paste is a fluent or plastic mixture of a solid and liquid, similar to how the groundmass is a solid paste-like substance made up of minerals and rocks. These synonyms help to describe the composition of the groundmass and its role in the formation of igneous rocks.
