zero hour

noun

1. the time set for the beginning of a military attack or operation.
2. the time set for the beginning of any event or action.
3. a decisive or critical time.

zero hour

noun

1. military the time set for the start of an attack or the initial stage of an operation
2. informal.
   a critical time, esp at the commencement of an action

Word History and Origins

Origin of zero hour¹

First recorded in 1915–20

Example Sentences

Moreover, the "wellbeing" benefits of the measures, which include challenging the use of zero hours contracts and boosting sick pay, would amount to £3bn, it found.

From BBC

Workers who prefer zero hours would be able to refuse - there will be no obligation to accept.

From BBC

Then there is the question of banning "exploitative" zero hours contracts.

From BBC

The bill would offer "a genuine living wage and sick pay for the lowest earners" and ban "exploitative zero hour contracts and unpaid internships", she said.

From BBC

The proposed ban on all zero hours contracts had been diluted to banning "exploitative zero hours contacts" well before the election.

From BBC