From AikiWiki - AikiWeb Aikido Information
[edit] Aikido: 合気道
One interpretation of the word "Aikido" is that the word is made up of three Japanese characters: Ai 合 - harmony; Ki 気 - spirit, mind, or universal energy; Do 道 - the Way. Thus aikido has been called "the Way of Harmony with Universal Energy."
Some do not agree with this interpretation as the character for "ai" 合 itself does not connote "harmony" in Japanese but rather "to fit or to match." As such, "Aiki" 合気 may also be interpreted as "accommodation to circumstances"; this interpretation avoids certain metaphysical commitments and is an attempt to describe both the physical and psychological facets of aikido in everyday language.