I thought about this and here is the short version. (thankfully)
What is the meaning of aikido?
Of course the answer is going to be different from every person that practices aikido. There are many that answer with the standard party line that the seniors in whatever organization they belong to put forth. I think it is important for each one of us to really come to our own original answer to this if we are ever to develop real authority in our practice.
First of all, I think we really begin the practice of aiki jutsu. The artful or efficient practice of aiki is what I mean. Then, at some point, we begin to develop and see the "MICHI" or WAY of living our practice. The way we perceive and treat our self and others. Then for some of us it may go further and have something to do with the way we perceive and relate to the Universe. We may talk about and practice all of this in ways that often appear different and at odds with each other. That is the practice…we must all eventually come to our own answer. The rock solid knowing of what the meaning of aikido is for us.
The artful side of this practice is what I think of as "defending against aggression" and the discipline that this practice provides can be used to look within our self and begin to understand the human condition and our relationship with the Universe and each other.
The conclusions you come up with ultimately must be your own. The founder of what we think of as aikido, Morihei Ueshiba found his answer and told us all to find our own. It takes great courage and perseverance to even stay on the path. In my opinion, we will never complete the journey. Each step along the way is what is important.
Someone asked me, some time ago, to summarize this. All I could come up with is -- "Make your outsides match your insides, uplift all beings, and do as little harm as possible."