Recognition

One of Socrates' teachings was that everybody knows virtually nothing and that it is impossible for one to count as knowledgeable.  Where one everyday person might be an expert in mechanics, he would make a physicist look like an idiot when it came to fixing cars.  But Socrates also went a little deeper and always asked, "why?"  He realized that it is impossible for someone to know something in its entirety.  We may think we know something all the way down to its roots but there is always the never-ending "why?"
Therefore, to know something, means to recognize it.  To recognize an item means you are aware of its boundaries as well as its potential and how it relates to you.  We may think we know someone entirely but there will always be something out of our reach of comprehension.  We won't be able to understand and prove why this person does the things he or she does.  However, we recognize that person and all that we associate with him/her.  So if this hypothetical person does something others would view as strange- we might see it as perfectly normal because we recognize the limits of this person and we would be able to understand their actions because of our deep recognition.
To make Socrates proud, being knowledgeable means to recognize that we know nothing at all.  No one person will ever know every fact ever.  Like the earlier example, I may know tons of stuff about physics and science and math- enough to outsmart the "Average Joe" plumber; but once it comes to pipes and such- the plumber is clearly superior.