Refers to an extremely short period of time, often used in literary or dramatic contexts. Can function as a noun or adverbially with に.
from Sanskrit kṣaṇa
Her expression changed in an instant.
In that moment, I couldn't understand what had happened.
kshana; shortest possible interval of time
Buddhist term for the smallest unit of time, originally defined as the duration of a single mental event (about 1/75 second). Rare outside specialized contexts.
In Buddhism, kshana is considered a unit representing a single momentary movement of the mind.
The instant the door opened, she screamed.
In that instant, it felt as if everything had changed.
一瞬 is often used adverbially as 一瞬で／一瞬にして in everyday speech, whereas 刹那 carries a heavier, more poetic weight and appears less in casual conversation.
束の間 describes a fleeting span of time that still has a slight duration, while 刹那 stresses an instant so brief it is almost point-like.
Standard kanji spelling; the most common written form.
Irregular kanji usage (ateji); rarely used and not recommended for learners.
Borrowed from Sanskrit kṣaṇa via Buddhist texts. The kanji 刹 (setsu) and 那 (na) are used phonetically (ateji) to represent the sound. The original Buddhist meaning refers to an extremely short unit of time.