abysso-, abyss-, abys- +

1. Without a bottom; bottomless (no bottom).
2. Anything too deep for measurement.
3. An immeasurably profound depth or void; "a bottomless pit".

1. Immeasurably deep, severe, or extreme; fathomless.
2. Informal, extremely bad or of very low quality; such as, "abysmal ignorance".
3. Incapable of being measured or even understood; incomprehensible, inscrutable.
4. Etymology: from the year 1656, formed in English from obsolete abysm, "bottomless gulf, greatest depths"; from Old French abisme, from Vulgar Latin abyssimus.

In a terrible manner; very bad.

1. A bottomless pit.
2. Anything too deep or too great to be measured; lowest depth.
3. An immeasurably deep chasm, depth, or void.
4. The primeval chaos out of which it was believed that the earth and sky were formed.
5. The abode of evil spirits; hell, thought of as a bottomless pit.

Strictly speaking, the abyss is a particular zone extending between 3,000 and 6,000 meters (9,840 and 19,680 feet at 3.28 feet per meter) in depth. By extension, the term is also used to designate the deep oceans everywhere.

1. Of or inhabiting the depths of the ocean to which light does not penetrate; unfathomable.
2. In oceanography, of or relating to the deepest regions of the ocean and the organisms inhabiting that environment; at depths between 4 000 and 6 000 meters.

In oceanography, of or relating to the ocean floor in the abyssal zone.

Flat, sediment-covered areas in the deep ocean basin, usually at depths between 3,000 and 5,000 meters.

1. Pertaining to, or found on, the bottom of the ocean at depths exceeding ca. 1 000 meters (British: metres).
2. Living on or in the ocean floor in the abyssal zone or the great depths in the oceans or lakes into which light does not penetrate; commonly used in oceanography of depths between 4 000 and 6 000 meters.

A large mass of intrusive igneous rock having an exposed surface area of more than forty square miles, with no apparent base or floor of older rock. Part of the vocabulary used in the science of petrology.

1. A reference to the region of deep water which excludes the ocean floor; floating in the ocean depths. Living in the oceanic water column at depths of between 4,000 and 6,000 meters (metres) [13,120 feet to 19,680 feet], seaward of the shelf-slope break.
2. Of or relating to organisms or phenomena in mid-water, but still at great depths.

One misstep leads to another.

Literally, "Hell calls hell." A warning that the first step in the temptation to go astray from what is "right" (or "morally correct") is difficult to prevent; however, we must always be on guard to strive for what is ethical and honorable.

1. A description of igneous rocks; especially, in the form of dikes or sills, created when molten magma rose to the surface of the earth's crust but solidified before reaching it.
2. Designating a rock in texture that is intermediate between plutonites (a deep-seated rock) and extrusive rocks (forced out at the surface) which are usually formed at moderate distances below the surface; part of the vocabulary used in the science of petrology.
3. Solidifying chiefly as a minor intrusion, especially as a dike or sill (a vertical or near-vertical mass of igneous rock that has forced its way upward through overlying strata), before reaching the earth's surface; a reference to rocks.