noun
the whole world; the entire universe
A yojijukugo (four-character compound) meaning the entire world or universe, often used in Buddhist or literary contexts to express vastness or totality.
一天四海の平和を願う。
I pray for peace throughout the whole world.
この教えは一天四海に広まった。
This teaching spread across the entire universe.
A yojijukugo composed of 一 (one), 天 (heaven), 四 (four), and 海 (sea), literally 'one heaven, four seas'. The phrase originates from Buddhist cosmology, where it refers to the entire world or universe under one heaven and surrounded by four seas.