The Collaborative International Dictionary of English v.0.48:
Noon \Noon\ (n[=oo]n), n. [AS. n[=o]n, orig., the ninth hour,
fr. L. nona (sc. hora) the ninth hour, then applied to the
church services (called nones) at that hour, the time of
which was afterwards changed to noon. See Nine, and cf.
1. The middle of the day; midday; the time when the sun is in
the meridian; twelve o'clock in the daytime.
2. Hence, the highest point; culmination.
In the very noon of that brilliant life which was
destined to be so soon, and so fatally,
High noon, the exact meridian; midday.
Noon of night, midnight. [Poetic] --Dryden.