twelve o'clock; noon; midnight
Refers to the time of day at 12:00, either noon or midnight depending on context. Often clarified with 午前 (a.m.) or 午後 (p.m.).
The meeting starts at twelve o'clock.
He didn't come even after twelve o'clock.
Standard kanji spelling.
Arabic numeral spelling, common in schedules and digital displays.
Compound of 十二 (twelve) and 時 (hour/o'clock).