Definition

Adverb 1. Used to specify the hour when telling time: The word "o'clock" is used after a numeral to indicate the exact hour according to a clock or watch. It is a contraction of the phrase "of the clock."

Usage

"O'clock" is used exclusively to state the hour in time expressions. It is not used with minutes. For example, you say "three o'clock" but "three fifteen" or "a quarter past three," not "three fifteen o'clock."

Examples

• Adverb:
  • The meeting is scheduled for ten o'clock in the morning.
  • "What time is it?" "It's five o'clock."
  • The train departs at seven o'clock sharp.

Advanced Usage

• "... o'clock sharp": Used to emphasize that something will happen exactly at that hour, not a minute before or after.
  • Dinner will be served at eight o'clock sharp.
• "The ... o'clock news/meeting/train": Used to specify a regular event that occurs at a particular hour.
  • I always listen to the six o'clock news on the radio.

Variants and Related Words

• Clock (noun): A device for measuring and showing time.
  • The clock on the wall says it's noon.
• Clock (verb): To record the time of an event, or to achieve a certain time.
  • He clocked an impressive speed in the race.

Synonyms

• ... sharp (when emphasizing exactness):
• ... on the dot (informal, when emphasizing exactness):

Related Phrases

• Around the clock / Round the clock: Continuously, for 24 hours a day.
  • Doctors worked around the clock to help the victims.
• Like clockwork: With perfect regularity and precision.
  • The project proceeded like clockwork.
• Against the clock: Rushing to finish before a deadline.
  • We are working against the clock to complete the report.

Notes

"O'clock" is only used for the 12-hour clock system. In the 24-hour system (e.g., 15:00), "o'clock" is not used.

Adverb

1. according to the clock
   • it's three o'clock in Tokyo now