Catholic Encyclopedia (1913)/Abyss
Abyss is primarily and classically an adjective, meaning deep, very deep (Wisd., x, 19; Job, xxxviii, 16). Elsewhere in the Bible, and once in Diog. Laert., it is a substantive. Some thirty times in the Septuagint it is the equivalent of the Hebrew tehom, Assyrian tihamtu, and once each of the Hebrew meculah, "sea-deep", culah, "deep flood", and rachabh, "spacious place". Hence the meanings: (1) primeval waters; (2) the waters beneath the earth; (3) the upper seas and rivers; (4) the abode of the dead, limbo; (5) the abode of the evil spirits, hell. The last two meanings are the only ones found in the New Testament.