Twelve o'clock is a common phrase used to indicate that it's noon or midnight. However, there are several synonyms for twelve o'clock that can be used to add variety and interest to your language. Some synonyms for twelve o'clock include midday, high noon, noonday, meridian, midnight, witching hour, and bewitching hour. These words can be used interchangeably to convey the same meaning as twelve o'clock. For example, you could say "It's high noon" instead of "It's twelve o'clock" or "It's noonday." These synonyms can add a touch of elegance and sophistication to your language, so don't be afraid to experiment with them!