H-hour

American  

[eych-ou^uhr, -ou-er] / ˈeɪtʃˌaʊər, -ˌaʊ ər /

noun

Military.

1. the time, usually unspecified, set for the beginning of a planned attack.

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H-hour British  

noun

1. Also called: zero hour.  military the specific hour at which any operation commences

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Etymology

Origin of H-hour

First recorded in 1918; H (for hour ) + hour; D-day

Example Sentences

"There were formal projects led by trained scientists and researchers, such as the tide prediction mechanism created by British mathematician Arthur Thomas Doodson, which was used to identify the precise days/times that the H-Hour landings for D-Day should take place."

From Fox News

At H-hour on D-day, army chaplain Captain Leslie Skinner struck out for Gold beach.

From The Guardian

A: Many flights don’t get completely booked, and the airline struggles to sell those last empty pricey seats at H-hour.

From Fox News

Doyle moved to the Emerald City from Boise, Idaho, in the mid-’80s and formed his own group, H-Hour.

From Seattle Times

But a post H-Hour recording session with Endino, paid for with Doyle’s tax refund, was more fruitful.

From Seattle Times