Buddhist loanword from Sanskrit kṣaṇa — the smallest unit of time in Indian Buddhist cosmology. According to Xinhua, it originally meant the time it takes to spin a single length of thread. Entered Chinese with the spread of Buddhist sutras and is now fully naturalised.
usage
Often used in the fixed phrases 刹那间 ('in an instant') and 一刹那 ('one split second'). More poetic and dramatic than the everyday 一下子 ('all of a sudden') or 突然 ('suddenly').
