countdown

American  

[kount-doun] / ˈkaʊntˌdaʊn /

noun

1. the backward counting in fixed time units from the initiation of a project, as a rocket launching, with the moment of firing designated as zero.

2. the final preparations made during this period.

3. a period of increasing activity, tension, or anxiety, as before a deadline.

---

countdown British  

/ ˈkaʊntˌdaʊn /

noun

1. the act of counting backwards to time a critical operation exactly, such as the launching of a rocket or the detonation of explosives

---

verb

1. to count numbers backwards towards zero, esp in timing such a critical operation

Etymology

Origin of countdown

1950–55, noun use of verb phrase count down

Explanation

When you list a sequence of numbers in reverse order, ending in zero, that's a countdown. When you're preparing to launch your model rocket, you can make it more exciting with a countdown! "Five, four, three, two, one, blast off!" is a countdown that may sound familiar if you've ever watched footage of a NASA space shuttle launch. You might also hear a countdown on New Year's Eve, as revelers count down the seconds until midnight and the beginning of a new year. This word comes from American English, first appearing in the 1950s in the context of rocket launches.

Example Sentences

I happen to live and work in Melbourne, Fla. Our area code is 321 — like a countdown.

From MarketWatch • May 12, 2026

He clearly realized, as the countdown clock clicked on, that he had overstepped and was eager, even desperate, for an off-ramp.

From Slate • Apr. 8, 2026

They were all smiles as countdown clocks ticked and the Orion spacecraft flew ever closer to Earth's cratered neighbor, a mission years in the making come to fruition at last.

From Barron's • Apr. 7, 2026

Dearest gentle reader, the countdown to Francesca and Michaela’s season has officially begun.

From Los Angeles Times • Mar. 24, 2026

Tibbets picked up the intercom and said: “Put on your goggles. Place them up on your forehead. When the countdown starts, pull the goggles over your eyes and leave them there until after the flash.”

From "Bomb" by Steve Sheinkin