unfathomable
US /ʌnˈfæð.ə.mə.bəl/
UK /ʌnˈfæð.ə.mə.bəl/
1.
insondable, incompréhensible, impénétrable
incapable of being fully explored or understood
:
•
The depths of the ocean are still largely unfathomable.
Les profondeurs de l'océan sont encore largement insondables.
•
His decision to leave was unfathomable to his family.
Sa décision de partir était incompréhensible pour sa famille.