From Wikipedia:

Aikido (Japanese: 合気道? Hepburn: aikidō) [aikiꜜdoː] is a modern Japanese martial art developed by Morihei Ueshiba as a synthesis of his martial studies, philosophy, and religious beliefs. Aikido is often translated as “the way of unifying (with) life energy” or as “the way of harmonious spirit”. Ueshiba’s goal was to create an art that practitioners could use to defend themselves while also protecting their attacker from injury.

Aikido techniques consist of entering and turning movements that redirect the momentum of an opponent’s attack, and a throw or joint lock that terminates the technique.

The word “aikido” is formed of three kanji:

合 – ai – joining, unifying, combining, fitting
気 – ki – spirit, energy, mood, morale
道 – dō – way, path

Therefore, from a purely literal interpretation, aikido is the “Way of combining forces”, in that the term aiki refers to the martial arts principle or tactic of blending with an attacker’s movements for the purpose of controlling their actions with minimal effort. One applies aiki by understanding the rhythm and intent of the attacker to find the optimal position and timing to apply a counter-technique.