unfathomable

同义词：

deep | bottomless | enigmatic | abstruse | profound | unsounded | unplumbed | immeasurable | vast | incomprehensible | impenetrable | inscrutable | unknowable | indecipherable | arcane | mysterious | inexplicable | abyssal | abysmal |

反义词：

fathomable |

词义辨析：

同义参见:

deep

bottomless

enigmatic

abstruse