H hour

noun

: the hour set for launching a specific tactical operation

Word History

Etymology

H, abbreviation for hour

First Known Use

1918, in the meaning defined above

Time Traveler
The first known use of H hour was in 1918

Dictionary Entries Near H hour

H hinge

H hour

HHS

See More Nearby Entries 

Cite this Entry

“H hour.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/H%20hour. Accessed 21 Dec. 2024.

Copy Citation

Share

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Popular in Grammar & Usage

See All

Point of View: It's Personal

Plural and Possessive Names: A Guide

What's the difference between 'fascism' and 'socialism'?

More Commonly Misspelled Words

Words You Always Have to Look Up
See All

Popular in Wordplay

See All

8 Words with Fascinating Histories

8 Words for Lesser-Known Musical Instruments

Birds Say the Darndest Things

10 Words from Taylor Swift Songs (Merriam's Version)

10 Scrabble Words Without Any Vowels
See All

Games & Quizzes

See All
Play Quordle: Guess all four words in a limited number of tries. Each of your guesses must be a real 5-letter word.
Quordle Can you solve 4 words at once?
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.
Blossom Word Game Pick the best words!
Play Missing Letter: a crossword with a twist. Each of the 25 puzzle words start with a different letter of the alphabet. Which letter is missing?
Missing Letter A daily crossword with a twist
naughty or nice
Are you naughty or nice? Quiz He's making a quiz, and checking it twice...