a. Pertaining to, or resembling, an abyss; bottomless; unending; profound. [ 1913 Webster ]
Geology gives one the same abysmal extent of time that astronomy does of space. Carlyle. [ 1913 Webster ]
adv. To a fathomless depth; profoundly. “Abysmally ignorant.” G. Eliot. [ 1913 Webster ]