O Sensei Moirhei Ueshiba was reported to have said, when asked about the meaning of aiki, "When I move around, that is what aiki is."
Much of what he said is up for interpretation - nobody knows just what he was thinking most of the time - and this one is no different. But I'd like to offer a possible glimmering of understanding for this particular statement.
I think perhaps Ueshiba was saying something like, "Look! Aiki lives within the movements - not in the techniques! It is the relative movements of uke's and tori's bodies that makes aiki."
I was watching an instructional video by Bram Frank, and he said something that put me in mind of this quote and led me to this interpretation. He said, and I paraphrase, "This is all movement. The techniques will not keep you from being cut. Movement will keep you from being cut. It is the movement that will save you - not the techniques."