eight o'clock

Short definition from Wiktionary

Noun

1. 1
   The start of the ninth hour of the day; 8:00 a.m. (08:00).
2. 2
   The start of the twenty-first hour of the day; 8:00 p.m. (20:00).
3. 3
   A position to the left and behind (horizontal clock orientation) (from the location of the 8 mark on a clock face)