Definition of unplumbable in US English:

unplumbable

adjective

  • See unplumbed

    • ‘While I have never doubted the unplumbable dumbness of the Littlest Caesar, the real surprise is that his bosses, like Dick Cheney and Donald Rumsfeld, aren't the evil geniuses we thought they were.’
    • ‘She looked smooth and precious, a thing of unplumbable mysteries, and perilous as quicksand.’
    • ‘This is a talent of unplumbable dimensions.’
    • ‘Well, first of all, the diary is a terrific introduction to the wondrous complexity of one's unplumbable soul.’
    • ‘Its future does not rely on the generosity of investors with pockets of unplumbable depth.’

Pronunciation

unplumbable

/-ˈpləməbəl/