When I first think of the word "sin" I think of some fire and brimstone sermons I've listened to over the years, I think of a list of offenses: murder, theft, anger, lust, pride, and more, but more and more when I think of sin - I think of it being the thing or things that can be a barrier to all the things that are listed as the fruit of the spirit: love, joy, peace, patience, kindness, goodness, humbleness, and self-control.
In the last year it seems I'm in the process of being realigned by the compass of Jesus words here in John 13:34 "A new command I give you: Love one another. As I have loved you, so you must love one another. 35By this all men will know that you are my disciples, if you love one another."
When it comes to the matter of sin, I think much of it would be resolved if we, as in I, lived in the way of love like Jesus speaks of more and more on a daily basis. Sometimes I think it is easier to define what something, like sin, is with what it isn't - and sin isn't anywhere close to love.