noon

The word "noon" presents a fascinating semantic shift. It originates from the Latin phrase "nōna hōra," meaning the ninth hour of the Roman day, which began at sunrise and was counted from 6 a.m., placing the "ninth hour" at approximately 3 p.m. This timing was significant in Christian liturgy for the prayer service of Nones. In Old English, the term was adopted as 'nōn' to designate this canonical hour. Over centuries, the time for the prayer service was moved earlier in the day, and by the 12th century, the meaning of "noon" had shifted to refer to the time of the midday meal and eventually settled on its current meaning of 12 o'clock midday. The journey from "ninth hour" to "midday" illustrates how religious and social practices can fundamentally alter the meaning of a word.

The word is a simplex form. It derives from the Old English 'nōn', which referred to the ninth hour of the day from sunrise (approximately 3 p.m.). This term was borrowed from the Latin 'nōna (hōra)', meaning "ninth (hour)".