Isshun

Isshun (Japanese: 一瞬)

Isshun refers to a very short period of time; an instant, a moment, or a flash. It implies an extremely brief duration, so fleeting that it's almost imperceptible. The term is derived from Buddhist philosophy where it represented the shortest possible unit of time.

The concept of isshun is often used to describe moments that are beautiful, decisive, or transformative, emphasizing their ephemeral nature. It can also highlight the speed or immediacy of an action or event. It's a commonly used word in everyday Japanese conversation, literature, and media.

While there is no precise equivalent in English, "instant," "moment," "flash," "split second," and "blink of an eye" are all approximations depending on the context. The nuance of isshun often carries a sense of transience and value.