Midday is twelve of clock noon. What comes after midday is after-midday, or the afternoon. The abbreviation p.m. means post meridiem, or post midday.

Midday is 12 noon or 12 midday. It is not 12 p.m. as p.m. means 'after midday'; nor is it 12 a.m. as a.m. means 'before midday. Logically, midday cannot be before or after midday. Similarly, midnight is 12 midnight.

midday

There are 48 hours from midday on Friday to midday on Sunday.

We break for lunch at midday.