Well, here's my two cents....
As others have mentioned, the literal translation is meeting,spirit, and way. But take those words with a grain of salt too. I don't like how the "Ai" is often misconstrued to mean "harmony". "Ki" is another one, as others have mentioned that is difficult to pin down. As for "Do" I don't like using it as a "the way of....". It sounds so light-hearted and more like a method, or a means to accomplish things, rather than a serious moral discipline.
Also, I believe many have misunderstood the term "aiki" to mean joining with the ki of the attacker. However, according to some like Tohei and Kisshomaru, it actually refers to the joining of the ki of the mind with the ki of the body to become one. Ultimately, the goal is the become one with the universal ki. I am curious if this definition of aiki is the same as the one used in other "aiki" arts, such as Daito-ryu aiki-jutsu.
While it is worthwhile to understand the meaning of the name, it is, just a name. From what I understand, it sounds like Ueshiba wasn't even the one to name the art he created.
As a musician the word harmony has a different conotation than it does for many others who do not study music. When we begin to combine the practical aspects of harmony, as they are revealed in music, with the concept of a 'drone tone' we can see how the constant vibration of the universe (ki) defines the environment that we have to unite to (harmony). A study of Kotodama (sound, syllable vibration as creative basis ) reveals the ties between the harmony of which we speak and the ways that we can utilize it. Perhaps this might help. Spirit is the feeling of the sound and playing the instrument is the physical practice. Kinda hard to isolate the two in composition.
My 2 cents:
Before we begin to feel to fluffy in the sneakers about our use of 'Do', we might consider how deadly some passes can be on this nature hike. Speaking of nature: the equivalent of DO is Tao, written
frequently translated as 'unobstructed nature'.
Simply because we don't yet understand something does not mean we should discard that teaching or take a stance for or against it. I believe we should stay humble and continue to seek to come to a new place of renewed understanding.