Noun
H-hour (plural H-hours)
(figuratively) The hour at which any major event planned for the future is set to begin, as used in United States military.
The remaining eight Sheridans were delivered to Torrijos-Tocumen Airport some hours after H-hour by Low-Velocity Airdrop ( LVAD ) technique from C-130 transports. Source: Internet
Relations were further soured with reports from a number of publications that Osama bin Laden might have escaped due to a substantial delay from the original H-hour of the deployment of American Forces. Source: Internet
I was tasked to get the team inside and secure prior to “H-Hour.” Source: Internet