o'clock

adverb3

1. •
   In conjunction with a numeral, indicates the time within a twelve-hour period (midnight to noon or noon to midnight), specifically the time when the hour hand of a clock points precisely to the symbol or marking corresponding to the designated numeral, i.e., at the hour.

   • We are expected to be there at six o'clock in the morning!
   • It is two o'clock.
2. •
   (informal, humorous) Used to indicate that it is time to do a specific action, or time for a specific action to occur.

   • I'm feeling peckish; I think it must be nearly dinner o'clock.
   • We're here at Waffle House, and it's waffles o'clock!
3. •
   In conjunction with a numeral, indicates the direction, relative to the speaker or a vehicle, especially an aircraft, corresponding to the direction the hour hand is pointing at the time corresponding to the numeral, with twelve representing directly ahead on a horizontal plane, or directly up on a vertical plane, and three being to the right on either.

   • It's at nine o'clock about two feet in from the edge of the branch. You need to know your "o'clocks" (nondigital) to spot birds. — 1989