o'·clock 
/əˈklɑ:k/ adverb
/əˈklɑ:k/ adverb : according to the clock — used when the time is a specific hour ▪ It's three o'clock in the afternoon. [=it's three p.m.] ▪ She was 10 minutes late for her 8 o'clock appointment. ▪ Be here at nine o'clock, not at nine fifteen.
