四六時中 (しろくじちゅう) Japanese meaning | Kotomora彼は四六時中仕事のことを考えている。
He thinks about work around the clock.
This shop is open day and night.
Work has been so busy lately that I'm exhausted around the clock.
終始
N2
終始 means 'from beginning to end' and is more literary/formal, while 四六時中 is a vivid, colloquial idiom about ceaseless 24-hour activity.