Lack of specific knowledge
unawareness, unconsciousness, unfamiliarity, incomprehension, bewilderment, incapacity, inexperience, simplicity, disregard, obliviousness, insensitivity, sciolism, nescience, shallowness, superficiality, confusion, fog, vagueness, half-knowledge, a little learning, no more than a tyro's background, greenness; see also sense 2, confusion 2.
Antonyms ability*, learning, erudition.
Lack of general knowledge
illiteracy, unenlightenment, mental incapacity, denseness, dumbness, empty-headedness, crudeness, barbarism, philistinism, vulgarity, obtuseness, unfamiliarity, unintelligence, rawness, benightedness, superstition, darkness, blindness, simplicity, innocence, stolidity, unscholarliness, functional illiteracy, know-nothingism, lack of learning, lack of education, lack of erudition, lack of information; see also sense 1, stupidity 1.
Antonyms knowledge*, acquaintance, understanding.