noon; 12 PM
Formal or written expression for exactly 12:00 noon. In casual speech, 正午 (しょうご) or 昼の12時 is more common.
The meeting starts at noon.
The siren sounded exactly at noon.
午後零時 is a formal, official way of writing noon on schedules, while 正午 is the everyday equivalent.
Compound of 午後 (ごご, 'afternoon') and 零時 (れいじ, 'zero hour'), literally 'afternoon zero hour', meaning 12:00 PM.