ten o'clock

(In both the 12-hour clock and the 24-hour clock) The start of the eleventh hour of the day; 10:00 a.m. (10:00).

(Only in the 12-hour clock) The start of the twenty-third hour of the day; 10:00 p.m. (22:00).

(informal) A position to the left and slightly ahead (horizontal clock orientation) (from the location of the 10 mark on a clock face)