all night; throughout the night
Used as a noun or adverb to describe something lasting the entire night. Often appears in formal or written contexts.
終夜、雨が降り続いた。
It rained all night.
He worked throughout the night.
終夜 is a formal, written equivalent of 一晩中, often seen in signs like 終夜営業 (open all night) rather than in casual speech.
night light
open all night; all-night business
all-night service; overnight operation
Compound of 終 (end, throughout) and 夜 (night). The reading しゅうや is the on'yomi of both characters.