five o'clock

five o'clock (uncountable)

1. (In both the 12-hour clock and the 24-hour clock) The start of the sixth hour of the day; 5:00 a.m. (05:00).

   The breakfast buffet opens at five o'clock (= "The breakfast buffet opens at 5:00 a.m.").

2. (Only in the 12-hour clock) The start of the eighteenth hour of the day; 5:00 p.m. (17:00).

   The next train comes at five o'clock (= "The next train comes at 17:00").

3. (informal) A position behind and slightly to the right (horizontal clock orientation) (from the location of the 5 mark on a clock face)

   We've got a bogey at five o'clock.

• five o’clock shadow (“it's five o'clock somewhere”)