say it: uhn-FATH-uh-muh-buhl
unfathomable is an adjective meaning "of depth; not capable of being sounded or measured". It carries 3 recorded senses.
of depth; not capable of being sounded or measured
incapable of being fully understood
Definitions, synonyms and semantic relations for unfathomable come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.