Kairos

Kairos is an [ancient Greek] word meaning the "right or opportune moment". It is now used in [theology] to describe the qualitative form of [time]. In [rhetoric] kairos is "a passing instant when an opening appears which must be driven through with force if success is to be achieved." (E. C. White, Kaironomia p. 13)

In theology
Kairos is the time which cannot be measured, the perfect time, the qualitative time, the perfect moment, the "now", the being.

It differs from [chronos] (kronos), which is the time that can be measured for example in seconds, minutes, hours, days.

Many Catholic churches and Catholic schools have "Kairos Spiritual Retreats." In this sense, kairos is adapted to mean "God's time," as per the Bible.

Kairos is also the name of an international Christian prison ministry.

In rhetoric
Kairos is very important in Aristotle's scheme of rhetoric. Kairos is, for Aristotle, the time and space context in which the proof will be delivered. Kairos stands alongside other contextual elements of rhetoric: The Audience which is the psychological and emotional makeup of those who will receive the proof; and, To Prepon which is the style with which the orator clothes their proof.

Compare the use of kairos in rhetoric to the use of kairosis in literary aesthetics.