The definition of maai is: "The spatial distance between one's self and the opponent. The gap between two opponents."

Related to the spatial 'maai' term is a similiar term 'ma' which translates to: " The space between two objects, events, or times"

Although both terms of maai and ma sound very similiar yet they are very different in practice. The most commonly used measure for maai is the shinai (see below) this distance is used regulate a proper spacing before a strike. The maai or spatial distance during keiko or free practice is always in transition from being too close to strike being being too far to strike, by becoming aware of the exact distance you are able to strike is vital as you begin your attack. Only through experience and constant practice will you be able to fine tune the distance in which you are able to strike and through observation what the striking distance for different opponents are.

By contrast the 'ma' term is used to describe how one actually times and distances oneself when delivering a kendo technique, such as oji waza or shikake waza. Without proper 'ma' your techniques will not be successful, it is the difference between a smoothly executed technique and one that appears clumsy, off timing so that you are too close or too far from the opponent. Timing and spacing in kendo techniques vary vastly from instantly striking to pause then strike, or strike, pause then strike again, or even parry and striking in different timing and spacing and so on.

Kokoro no maai is defined as a lapse in awareness. This lack of awareness occurs at any spatial distance. Classic lapse of awareness or kokoro no maai happens when the opponent begins or finishes an attack or strike, the mind is preoccupied with their technique at hand and the opponent is likely to be vulnerable.

Maai or the distance between opponents, in kendo maai or space/distance is manipulated to one's advantage. Beginners often take many years to develop awareness and appreciation of maai and its value. Maai and Ma is acquired through constant practice of kendo techniques.