Why Do We Say “O’Clock”? The Fascinating History Behind an Everyday Expression

The English language is filled with unusual details. Some words that look as though they should sound alike, such as come and home, are pronounced differently. Others, like tear and tear, have the same spelling but different pronunciations and meanings.

English also contains colorful expressions such as “raining cats and dogs” and “going cold turkey,” phrases whose origins aren’t always obvious.

One everyday expression that most people rarely question is o’clock. We use it whenever we tell someone the time, but have you ever wondered what the “O” actually means?

Its story goes back hundreds of years.

What Does “O’Clock” Actually Mean?

The “O” in o’clock is a shortened form of the older expression “of the.”

For example, when you say:

It’s three o’clock.

The phrase originally had the form:

It’s three of the clock.

In simple terms, it referred to the hour according to the clock.

Although “three of the clock” sounds strange to modern English speakers, this type of wording was once commonly used.

Why Did People Say “Of the Clock”?

Before mechanical clocks became widespread, people used several different methods to estimate the time.

These included:

• Sundials
• Water clocks
• Candle clocks
• Hourglasses
• The position of the sun and shadows

As mechanical clocks became more common in Europe during the Middle Ages, people increasingly used them as a specific reference for telling time.

The expression “of the clock” helped indicate that the stated hour was the time shown by a clock rather than an estimate based on the sun or another method.

How Did “Of the Clock” Become “O’Clock”?

Languages naturally change as people use them. Frequently spoken phrases often become shorter and easier to pronounce over time.

Instead of repeatedly saying something like:

Five of the clock

speakers gradually shortened the expression to:

Five o’clock

Eventually, the shorter version became the normal way of expressing the time, while the longer phrase disappeared from everyday conversation.

This kind of linguistic shortening is common in many languages. Words and expressions can become more compact when people use them frequently.

Why Does “O’Clock” Have an Apostrophe?

The apostrophe provides a clue about the word’s history.

In English, apostrophes are often used to indicate missing letters in contractions, as in:

• do not → don’t
• cannot → can’t
• it is → it’s

In o’clock, the apostrophe indicates that part of the original expression has been omitted.

Most people today don’t consciously think about the missing words, but the apostrophe remains as a small reminder of the expression’s older form.

Other English Expressions With Similar Origins

O’clock isn’t the only familiar English expression that preserves an older contraction.

Jack-o’-Lantern

The expression jack-o’-lantern is traditionally connected with an older phrase meaning Jack of the lantern.

The term originally had associations with people carrying lanterns and mysterious lights seen at night. Over time, its meaning became strongly associated with the carved pumpkin used during Halloween.

Will-o’-the-Wisp

Will-o’-the-wisp is another expression with an old-fashioned structure.

It refers to mysterious lights historically reported around marshes and other wet areas. These strange lights inspired folklore and stories about travelers being led astray.

Ne’er-Do-Well

The word ne’er is an old shortened form of never.

Therefore, a ne’er-do-well literally describes someone who “never does well.” Today, it generally refers to a person considered irresponsible, unsuccessful, or unreliable.

Why Is English So Full of Strange Expressions?

English has developed over many centuries and has absorbed vocabulary and influences from numerous languages, including French, Latin, Norse, and Germanic languages.

As the language evolved, pronunciation and grammar changed, while some older spellings and expressions remained.

This history helps explain why English has so many unusual features, including:

• Silent letters
• Different pronunciations of the same spelling
• Words with multiple meanings
• Old contractions that are still used today
• Expressions whose original meanings have changed over time

These inconsistencies can sometimes make English difficult to learn, but they also make the language fascinating.

The Takeaway

The next time you say “It’s six o’clock,” you’re using an expression with centuries of history behind it.

The “O” in o’clock comes from the older phrase “of the clock.” What once served as a way to specify that the time was being given according to a clock eventually became a short, everyday expression.

It’s a tiny detail that most people never stop to consider, yet it offers an interesting glimpse into how language changes.

Sometimes, even the simplest words we use every day can carry a surprisingly long history.