three o'clock
noun1
The start of the fourth hour of the day; 3:00 a.m. (03:00).
In both the 12-hour clock and the 24-hour clock
- The front desk closes at three o'clock (= "The front desk closes at 3:00 a.m.").
2
The start of the sixteenth hour of the day; 3:00 p.m. (15:00).
Only in the 12-hour clock
- The next train comes at three o'clock (= "The next train comes at 15:00").
3
Informal To the right (horizontal clock orientation) (from the location of the 3 mark on a clock face)
- We've got a bogey at three o'clock.