Definition

The fine-grained or glassy material in which larger crystals are found in certain types of rocks.

Example

The geologist examined the groundmass to understand the rock's formation.

Conversation

I was reading about different types of rocks today.

Oh really? Did you come across anything interesting?

Yes, I learned that groundmass is the fine-grained base of porphyritic rocks.

That's cool! I didn't know that — it sounds fascinating.

Synonyms & Antonyms

Root Explanation

Groundmass is formed from "ground" (from Old English *grund*, meaning bottom or foundation) and "mass" (from Latin *massa*, meaning lump or mass). The word refers to the solid material that forms the bulk of a rock or other substance, essentially the foundational mass.

Memory Tip

Think of the 'ground' as the bottom or foundation and 'mass' as a lump of material — together, they describe the solid material that makes up a rock.

Visually Confused Words