Definition of Friendship

TVJunkie's shout-out to our friendship caused me to wonder. What is the true definition of friendship? Here's what dictionary.com says:

1. The quality or condition of being friends.
2. A friendly relationship
3. Friendliness; good will
4. The state of being friends

After seeing a good share of concerned looks from friends and family when I'd planned to visit TV last week in LA, I wondered why they considered it so unusual to call someone a friend when you've never met them, nor even spoken with them on the phone. Did such looks arise when pen pals called each other friends? What truly defines friendship for you???

What is a friend? A single soul dwelling in two bodies.
~Aristotle
Some people go to priests; others to poetry; I to my friends.
~Virginia Woolf
Friendships begin because, even without words, we understand how someone feels.
~ Joan Walsh Anglund
The finest kind of friendship is between people who expect a great deal of each other but never ask it.
~Sylvia Bremer
There is magic in long-distance friendships. They let you relate to other human beings in a way that goes beyond being physically together and is often more profound.
~Diana Cortes