Countdown (noun)

1. The act of counting backwards to zero before an event, such as a rocket launch or a New Year's Eve celebration.
2. A sequence of numbers or words that counts down to an event.
3. The time remaining before an event.

Origin:

A count-down is the act of counting down to an event, such as a rocket launch. the word is a compound of "count" and "down".

Examples:

1. We heard the countdown over the loudspeakers as we watched the rocket launch.
2. The children began their own countdown as they waited for the fireworks show to begin.
3. I have a countdown timer on my phone to remind me when my flight leaves.
4. We started the countdown for the New Year with 10 seconds remaining.
5. The countdown to the end of the school year has begun.