The commencement of work, especially the start of construction or building work; often marked by a groundbreaking ceremony.
新しい橋の起工式が来週行われる予定だ。
The groundbreaking ceremony for the new bridge is scheduled for next week.
雨のため起工が一日遅れた。
The start of construction was delayed by one day due to rain.
会社は工場の起工を正式に発表した。
The company officially announced the commencement of construction for the factory.