My sister forwarded this to me today:
 
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Main Entry: friend
Function: noun

1:  one attached to another by affection or esteem
2 : one that is not hostile
3 : a favored companion
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Lately I've been having some trouble defining what a good friend is and how much one should go through before deciding that it is no longer a friendship that you want to have.  I don't think it's as simple as the above definition (though that'd be nice)..