three o'clock

noun3

1. •
   The start of the fourth hour of the day; 3:00 a.m. (03:00).

   • 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).

   • 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.