hypogeal

As a noun hypogea

is .

As an adjective hypogeal is

existing or growing underground.

As adjectives the difference between hypogean and hypogeal

is that hypogean is existing or growing underground while hypogeal is existing or growing underground.

As a noun taxonomy

is the science or the technique used to make a classification.

As an adjective hypogeal is

existing or growing underground.

As adjectives the difference between underground and hypogeal

is that underground is below the ground; below the surface of the Earth while hypogeal is existing or growing underground.

As an adverb underground

is below the ground.

As a noun underground

is an underground railway.

As a verb underground

is to route electricity distribution cables underground.

As a proper noun Underground

is the London Underground.