inground

As a noun trench

is a long, narrow ditch or hole dug in the ground.

As a verb trench

is (usually|followed by upon) to invade, especially with regard to the rights or the exclusive authority of another; to encroach.

As an adjective inground is

inside the ground.

As a noun terms

is .

As an adjective inground is

inside the ground.

As adjectives the difference between underground and inground

is that underground is below the ground; below the surface of the Earth while inground is inside the ground.

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.

As adjectives the difference between unground and inground

is that unground is not having been ground, unpulverized while inground is inside the ground.

As a verb unground

is (electricity|electronics) to remove a connection to ground potential.