The martial arts Aikido have its origin in Budo. This means all Japanese martial arts techniques with and without weapons which arose during the time of the Samurai (since the 11. century). Samurai were Japanese knights who could fight with their swords and even without weapons.
Budo not only means pure fighting techniques but a philosophy. This was important for an effective defence, too. If e. g. a fighter had fear of death, he could be hindered applying his techniques. Therefore the word Budo is composed of the term Bu = fight and Do = way. Do was understood as way to knowledge and mental maturity. At the end of the Samurai time such fighting techniques were not needed any more and remained as pure sport.
Grand master Morihei Ueshiba (1883 - 1969) developed Aikido from different fighting techniques to a weaponless self-defence technique. One aim was not to hurt an enemy. The word Aikido is composed of the syllables Ai, Ki, Do and has the meaning harmony (Ai), vital energy (Ki) and way to knowledge (Do). Aikido may also be understood to absorb the Ki of the attacker, combine it with the own Ki, intensify it to get harmony.