unsoundable
1. [ adjective ] too deep to determine the depth of
Related terms: unfathomable
Similar spelling:   unaccountable
  unsounded
  unconsolable
  uncombable
  unsoundness
  unconformable
  uncompounded
  unaccountably
  uncomparable
  uncontrollable
  unconscionable
  unconcealed
  unjointed
  uncounted