βυθός
buthos
boo-thos'
A variation of G899; depth, that is, (by implication) the sea
KJV Usage: deep.
G12 ἄβυσσοςἄβυσσος
abussos
ab'-us-sos
From G1 (as a negative particle) and a variation of G1037; depthless, that is, (specifically), (infernal) “abyss”