Noon (also midday or noon time) is usually defined as 12 o’clock in the daytime. The term midday is also used colloquially to refer to an arbitrary period of time in the middle of the day. Solar noon is when the sun crosses the meridian and is at its highest elevation in the sky, at 12 o’clock apparent solar time. The local or clock time of solar noon depends on the longitude and date. The opposite of noon is midnight.
The word noon is derived from Latin nona hora, the ninth hour of the day, and is related to the liturgical term none. The Roman and Western European medieval monastic day began at 6:00 a.m. (06:00) at the equinox by modern timekeeping, so the ninth hour started at what is now 3:00 p.m. (15:00) at the equinox. In English, the meaning of the word shifted to midday and the time gradually moved back to 12:00 local time (that is, not taking into account the modern invention of time zones). The change began in the 12th century and was fixed by the 14th century. Read more