"All Evil is Ignorance"

Plato wrote that very quote, "All evil is ignorance," yet the meaning can be deemed unclear through the use of meta-ethics. What is the meaning of ignorance? Harder yet, what is the meaning of evil?

Is evil that stereotypical thing, out to destroy the world? Is it Satan, formerly the angel Lucifer, who knows of God yet turned against him out of jealousy? Is evil living in an immoral means, and if so what is the complete definition of immoral? 

Presuming that ignorance means a lack of knowledge, and merely that (not a lack of understanding). And presuming that evil means....not eating vegetables when they are served to you?

Clearly not. Young children have quite the reputation for not eating vegetables. Furthermore food allergies exist, a valid reason to not do something, but it would still be evil to not eat them. But the reason would not be ignorance. It would be more pressing concerns, or in thecase of children a nonchalance toward the evil. I don't eat all the vegetables presented to me;  cauliflower, asparagus, and mushrooms are not on my list of food that I'm willing to eat. The reason is not that I am unaware that I should be grateful for food, so ignorance is not a valid argument for reason. 

Plato may indeed have had a point, that evil could be committed out of an ignorant mind, and only that way. Yet 'evil' is far too ambiguous of a word. It is straight out of a children's story--the evil stepmother wanting to harm the sweet princess, and the good prince riding in to the rescue at the last possible moment (as all good heroes must: see course Heroes 101). 

Philosophers clearly must consult meta-ethics before making statements. That way there are less arguments to made against them, when their works are a thousand years old!