abysmal (adj.) Look up abysmal at Dictionary.com
1650s, "pertaining to an abyss," formed in English from abysm + -al (1). Perhaps only a dictionary word before 19c. Weakened sense of "extremely bad" is first recorded 1904, perhaps from abysmal ignorance (suggestive of its "depth"), an expression attested from 1847. Related: Abysmally.