Lower.

Roget 207: low, neap, debased; nether, nether most; flat, level with the ground; lying low etc. v.; crouched, subjacent, squat, prostrate etc. (horizontal) 213.    ... show more

Dwelling beneath the surface of the earth:
— Nether regions.

synonyms: chthonian, chthonic.

Located below or beneath something else:
— Nether garments.

synonym: under.