I am wondering if there is any concensus on the word PORN.  What is porn?

I have always understood porn to be images or video of sexual activity.  I am beginning to understand that many people understand porn to mean nudity.  Is there a fine line that I missed somewhere? 

Is an image pornographic if it is sexually suggestive? 
If an artistic nude is not porn - what about it qualifies it to the non porn status? 
Can one be attempting to create an artistic nude and accidentally create porn?

Let the mayhem begin.

I suspected as much - thanks.