abysmal

adjectives

very great; limitless
"abysmal misery"; "abysmal stupidity"
abysmal
is similar to
impossible to measure
"unmeasurable reaches of outer space"
immeasurable, immensurable, unmeasurable, unmeasured
resembling an abyss in depth; so deep as to be unmeasurable
"the abyssal depths of the ocean"
abysmal, abyssal, unfathomable
is derived from
abysm