moment; instant
《Buddhism》kshana; duration of a single mental event (about 1/75 second); shortest possible interval of time
刹那の出来事が人生を変えた。
A single moment's event changed his life.
刹那に全てを判断しなければならなかった。
He had to make all the decisions in an instant.
爆発の刹那、彼は本能的に身を伏せた。
At the instant of the explosion, he instinctively threw himself to the ground.