Origin: Latin suffix -ous
Igneous has 4 different meanings across 1 category:
produced under conditions involving intense heat
"igneous rock is rock formed by solidification from a molten state; especially from molten magma"
"igneous fusion is fusion by heat alone"
"pyrogenic strata"
Pertaining to or having the nature of fire; containing fire; resembling fire.
The word comes from the Latin igneus, meaning "fiery." It was originally used to describe things related to fire.