Taking a look at the words for morning, afternoon and evening—בקר, צהרים, ערב—we notice that the word צהרים is different than the other two. The words בקר and ערב are in the singular whereas צהרים (literally this translates into “lights,” as צהר means light) is in the plural as is indicated by the suffix ים. What is the reason for this?
1) The Ramban
The Ramban tells us the reason for this discrepancy is due to the fact that in the morning the sun, the sun shines in the east while in the evening it is in the west. However, in the afternoon, when the sun is directly overhead, there is light on both sides. As a result, it is called צהרים, in the plural, signifying a time of total light.
2) Another explanation
Another explanation is that morning and evening are seen as unified periods with a single identity. They are distinct transitions: morning is the start of the day, and evening is its conclusion. The singular reflects their conceptual singularity and linear progression. On the other hand, the plural צהרים, afternoon, is inherently dual. This reflects its position between two halves of the day: the time after morning but before evening. The duality conveys the intermediate nature of this time period, linked to the sun's position being between its ascent and descent.
