How would you define 'friend'?

I have always loved being the only child, my Mom and I have this unbelievable relationship and I have always felt fulfilled by it. Being an only child has many perks; you don’t have to share your toys, you never try to measure up to someone else, and you have all of your parent’s attention and resources (just to name a few). There are also some drawbacks to being an only child; you have no one to share your toys with, there is no one to reminisce with about the good ole days, you are the only one to help aging parents, and (for me) you thirst for that closeness that siblings have. I believe it’s the ladder that has lead me to my current predicament. I have been disappointed in my some of my relationships lately and thanks to Tarzan, and many late night talks during our ‘kid-free’ time, I’ve realized that it may be due to my expectations.

Before now I never really noticed that I am an oddity. Out of all my close friends I am the only ‘only’. When I look at my friends with their families I know I don’t fit. I am their friend but I’ll never be in that inner circle with them. They HAVE a sister (or brother); they don’t need a sister/friend. I know I am no longer a minority lots of families (23 - 25% actually per Susan Newman, Ph.D.’s blog) are choosing to have only one child and many like my parents were given no choice. I have had this need for closeness in my life, to put it in Tarzan’s words, “People mean more to you than you do to them”. Though his words may have stung, knocked the wind out of me actually, they were true. It certainly helped to explain my dating life not to mention a lot of my friendships. I crave a sibling relationship. I want people in my life that don’t miss the milestones, not because it means something to me but because they are on this ‘journey’ with me. I do have people like this in my life but I also have some that I am trying to force along the way. Instead of unjustly harboring resentment toward these people I should assign them a ‘proper’ role in my life.

I have struggled with the decision Tarzan and I are making to have just one child, mostly I am sure we are doing the right thing but it’s moments like these where I desire more research. To help stop any future disappointments and to aid me in making an ‘informed decision’, I am on a quest to define ‘a friend’. What does it mean to people with siblings and those without? What are the differences in expectations for men and women? And how is that relationship different from a sibling (beyond the whole blood/relation thing)? Can a solid friendship fill the spot of a sibling?