Ki-ken-tai-ichi, from the Japanese kanji 気剣体一, describes the condition when all essential elements of a strike are unified in a single instant culminating in the perfect strike. The resulting strike, called the yuko-datotsu , or 有効打突, “valid strike”, is a goal all Budoka should strive to achieve.
Dissecting the Kanji into sub-parts can give a better understanding of the term’s meaning.
気, ‘ki’, is the kanji representing “spirt” or “energy”. In the context of ki-ken-tai-ichi, it represents the Budoka’s mental assertiveness and instinctive focus that both initiates and finalizes the strike.
剣, ‘ken’, is the kanji for “sword”. In ki-ken-tai-ichi it is naturally the actual instrument that manifests the mental (internal) and physical (external) intentions of the Budoka when executing a strike. As such, it should be regarded as an extension of the Budoka, not a separate disconnected element.
体, ‘tai’, is the kanji for “body”. In context, this represents the physical element of the Budoka’s intent – his body, the mechanism by which the mind’s intentions are executed resulting in the end goal.
一, ‘ichi’, the kanji for the number one (1). This is added to signify that the ‘ki’, ‘ken’, and ‘tai’ should not be considered separate elements at the moment of impact, but a single unified construct.