Aikido: A Brief Etymology

The word AIKIDO is composed of three Sino-Japanese ideographs:

    ai        harmony, coordination, or blending;
    ki        the universal life force of etheric energy of the universe; and
    do        a road or path; also implying a way of life.

Thus, among its many nuances is the meaning 'a way of life in harmony with the natural forces of the universe'.

AI   may be seen as a roof which shelters two other components.
The horizontal line is the number "one" and also means a single unit.  The square was originally a circle which was used to indicate a group.  The ideograph is a picture of a single family group in its house.  Thus, the meaning came to mean "to match" or "to blend" harmoniously like the members of a family under the same roof.
KI has two parts.  The upper portion shows three lines that formerly rose vertically from the fourth line.  The vertical lines represented steam rising from a surface.  Without the lower portion, this shape is a simple picture of steam rising from water or earth.  The lower part is the character for rice and displays the grains assembled on a central stalk.  For the ancient Chinese, steam rising from cooked rice was the very substance of life because without taking in this 'breath of life' one would starve.  Over time the meaning broadened and ki became a symbol of vitality or strength.  It was used in words implying willintention, and essence.  In oriental philosophy, it came to represent the fundamental energy of creation, the pervading essence of the universe, and the very life force itself.
DO means a road or path and also has two parts.  The right half shows two lines over another, perhaps eyes and a mouth.  The bottom portion is the character for the "self".  When used independently, this combined shape is a picture of the "neck" holding the head over the body.  The curved part at the left with the long tail is actually the character for the foot.  (The dot is the ankle bone and the "tail" represents the foot bones with the toes to the right.)  The complete character, then, shows the neck supported by the feet.  "One takes one's neck down the road with the feet."  This is a sentence used by children to remember the meaning of this character.  As the character began to be used philosophically, it acquired the nuance of taking you life into your hands and committing yourself to a particular path or vocation.  For over a thousand years this word has been used to symbolize the all encompassing path of religious or moral commitment; one's chosen "way of life".