Why is 12PM called noon?

Answer 1

The word "noon" is derived from the Latin word for NINTH. It was originally 9 hours after sunrise, which was the hottest part of the day.
The Romans usually had their lunch & rest at 3pm & it was called Noon.
As the industrial world developed, noon became the expression for when people "downed tools" to eat. So, noon, became the middle hour of the day.

Answer 2

The word Noon comes from the middle ages word
Non
[Middle English non, from Old English nōn. It was derived from the canonical hour of nones (3 P.M. in early Middle Ages), from Late Latin nōna (hōra), ninth (hour after sunrise), nones, or of Latin nōnus, ninth.]
It's a very old word from early England around 400ad
Why we use that word dose not make any sense because it use to refer to a time later in the day around 3pm.

Answer 3

Often wondered myself why the time after 12 noon was called 'afternoon', but the time before noon was called 'morning' instead of 'beforenoon.'

before.....noon.....after