o'clock

(not-comparable) 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.
(humorous, informal, not-comparable) Used to indicate that it is time to do a specific action, or time for a specific action to occur.
(not-comparable, with-numeral) 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.