Wow. Good question and I have been trying to define this all of my life! The definition of love for me-is different dependent upon the relationship. The love I have for my son is very different than the love I would have for a partner, boyfriend, lover, etc.
So...the beginning of a definition of "love" for someone in my life would have to be...the ability for both of us to fall backwards into each other on the worst of days and lifted up on the best of days. Exhibiting a healthy sense of giving (not to be confused with the co-dependent version: no mas) to the other...because I [I]want[I] to...