As an aside on those pesky words ...

Decimate got its 'modern' meaning not long after it was first coined, several centuries ago.
'Literally' first appeared in print to mean 'figuratively' just a few years after it first appeared, in the 14th century.
Noon comes from the monastic hour nones, and was about three o'clock in the, er, afternoon. (And if you're form round Hampshire or Isle of Wight way, 'nammet' = 'noon meat', i.e afternoon food.)
Like it or not, we're stuck with lots of words that have changed their meanings, often several times, over the centuries. Etymology isn't a good guide to usage.

... according to the full version of the Oxford English Dictionary.