1To make something happen later; to delay or postpone. (Transitive) Can also mean to set a clock back.
会議の開始を一時間遅らせることに決めた。
We decided to delay the start of the meeting by one hour.
雨のせいで出発を遅らせた。
We delayed our departure because of the rain.
時計を30分遅らせて、まだ正確な時刻になっていない。
I set the clock back 30 minutes, so it still doesn't show the correct time.
交通渋滞が到着を大幅に遅らせた。
Traffic congestion significantly delayed the arrival.