Merriam-Webster Logo
SINCE 1828
Menu
dictionary thesaurus

H hour

noun

Definition of H hour 

: the hour set for launching a specific tactical operation

First Known Use of H hour

1918, in the meaning defined above

History and Etymology for H hour

H, abbreviation for hour

Keep scrolling for more

Learn More about H hour

Dictionary Entries near H hour

hheth

HHG

H hinge

H hour

HHS

HI

hi

Statistics for H hour

Look-up Popularity

Time Traveler for H hour

The first known use of H hour was in 1918

See more words from the same year

More from Merriam-Webster on H hour

See words that rhyme with H hour

Comments on H hour

What made you want to look up H hour? Please tell us where you read or heard it (including the quote, if possible).

Show Comments  Hide Comments 

WORD OF THE DAY

linchpin

one that holds something together

Get Word of the Day daily email!

Test Your Vocabulary

Words from Greek and Roman Mythology Quiz

  • the-triumph-of-venus-by-alessandro-magnasco
  • Boreal comes from the name of the ancient Greek god of which wind?
How Strong Is Your Vocabulary?

Test your vocabulary with our 10-question quiz!

TAKE THE QUIZ
Syn City

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ

Love words? Need even more definitions?

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

Words at Play

Ask the Editors

Word Games