Synonyms of the word

abysmal

• adj. (now rare) Pertaining to, or resembling an abyss; unending; profound; fathomless; immeasurable.
• adj. (figuratively) Bottomless; extremely bad.

abyssal

• adj. (archaic) Belonging to, or resembling, an abyss; unfathomable.
• adj. (geography) Of or belonging to the ocean depths, especially below 2000 metres (6500 ft): abyssal zone.
• adj. (geology) Pertaining to or occurring at excessive depths in the earth's crust; plutonic.

deep

• adj. (heading, of a physical distance) Extending far away from a point of reference, especially downwards.
• adj. (heading, intellectual, social) Complex, involved.
• adj. (sound, voice) Low in pitch.
• adj. (of a color) Dark and highly saturated.
• adj. (sleep) Sound, heavy (describing a state of sleep from which one is not easily awoken).
• adj. Immersed, submerged (in).
• adj. Muddy; boggy; sandy; said of roads.
• adv. Deeply.
• n. (literary, with "the") The deep part of a lake, sea, etc.
• n. (rare) A deep shade of colour.
• n. (US, rare) The profound part of a problem.
• n. (with "the") The sea, the ocean.
• n. (cricket) A fielding position near the boundary.

immeasurable

• adj. impossible to measure.
• adj. vast.
• n. Anything that cannot be measured.

immensurable

• adj. unmeasurable, immeasurable; not able to be measured, therefore connoting extremely large.

unfathomable

• adj. Impossible to fathom or understand; incomprehensible.
• adj. Difficult to penetrate.

unmeasurable

• adj. Not able to be measured; immeasurable.