nine o'clock

nine o'clock (uncountable)

1. (In both the 12-hour clock and the 24-hour clock) The start of the tenth hour of the day; 9:00 a.m. (09:00).

   The breakfast buffet opens at nine o'clock (= "The breakfast buffet opens at 9:00 a.m.").

2. (Only in the 12-hour clock) The start of the twenty-second hour of the day; 9:00 p.m. (21:00).

   Supper was served at nine o'clock (= "Supper was served at 9:00 p.m.").

3. (informal) To the left (horizontal clock orientation) (from the location of the 9 mark on a clock face)

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