To toss my two cents in, I believe the translation works like this:
Ai - Harmony, esotiricly speaking love
Ki - Spirit, energy (energy of the universe)
Do - duh!, way (I think everyone nows that)
so it can be translated the harmonious spirit way or the way of the harmony (or harmonious) spirit.
What is important is to understand the philosophy trying to that Osensai was trying to teach, which is that one should be in harmony with the spirit of the universe, for if one was in perfect spiritual harmony with the universe, one could blend and become the universe. That is also why its a good reason to think of Ai as love as well, because love is what comprises as the spirit of the universe. In the situation of being attacked, you must have love for your opponent or you will not be with the universe, but when you are, what opponent can defeat the universe.