o'clock

When English speakers talk about an exact hour, they often use o'clock after the number: one o'clock, six o'clock, twelve o'clock. It means the time is exactly at that hour, with no extra minutes added. You usually hear it in everyday speech when someone says what time it is or when something starts. It is common, simple, and mostly used for the full hours, not times like six fifteen or six thirty.

O'clock is a time expression used after numbers from one to twelve to show an exact hour. If someone says three o'clock, they mean exactly 3:00. If they say ten o'clock, they mean exactly 10:00. It helps make the time clear and is one of the most common ways to talk about full hours in English.

You will usually see it in phrases about daily plans and routines: I wake up at seven o'clock, The meeting starts at nine o'clock, or We got home at eleven o'clock. It is natural in both speaking and writing, though in very casual contexts people sometimes leave it out and simply say at seven or by ten when the meaning is already obvious.

This expression is mainly used only for exact hours. English speakers normally do not use it with minutes, so we say three o'clock but not three o'clock twenty. For times with minutes, people usually say three twenty, a quarter past three, or half past three. That is an important part of using the expression correctly.

The form comes from the older phrase of the clock, which was shortened over time. That history explains the apostrophe. Today, most learners only need to remember the modern use: it goes after the hour number and shows that the time is exact.