As a language expert with a deep understanding of English grammar and usage, I can provide you with an in-depth explanation regarding the capitalization of the word "Sunday."
In English, capitalization rules can sometimes be a bit tricky, and the treatment of days of the week is no exception. The rules for capitalization in English are governed by a combination of grammatical conventions and historical practices. When it comes to the days of the week, including "Sunday," the general rule is that they are capitalized as they are considered proper nouns.

Step 1: English Explanation

The days of the week are unique in the English language as they are named after celestial bodies and deities from Roman mythology and Norse mythology. "Sunday" is derived from "Sun's day," named after the Sun. Similarly, "Monday" is named after the Moon ("Moon's day"), "Tuesday" after the Norse god Tyr ("Tiw's day"), "Wednesday" after Odin or Woden ("Woden's day"), "Thursday" after Thor ("Thor's day"), "Friday" after the Norse goddess Frigg ("Frigg's day"), and "Saturday" is named after the Roman god Saturn ("Saturn's day").

Because these names have a specific origin and are used to denote particular days that are distinct from one another, they are treated as proper nouns. In English grammar, proper nouns refer to specific people, places, organizations, or sometimes concepts, and they are always capitalized. This is why you will often see "Sunday" capitalized in formal writing, headlines, and other contexts where proper nouns are typically capitalized.

However, it's important to note that not all style guides agree on the capitalization of days of the week. Some style guides, particularly in British English, may advise against capitalizing days of the week when they are used in a general sense or as part of a sentence that is not emphasizing the day itself. For example, in a sentence like "I usually go to the park on Sunday," some might argue that "Sunday" should not be capitalized because it is not being used as a proper noun in the strictest sense.

On the other hand, American English style guides, such as the Associated Press (AP) Stylebook, typically recommend capitalizing days of the week regardless of how they are used in a sentence. This is because the days of the week are considered proper nouns due to their etymology and the specificity they convey.

In addition to days of the week, months are also capitalized as proper nouns. This is because each month has a unique name and represents a specific period of time. Seasonal names, however, are not capitalized because they do not refer to specific, unique entities but rather to general periods characterized by certain weather conditions.

Regarding school subjects, the general rule is not to capitalize them unless they are the names of specific languages. So, "math" and "algebra" are not capitalized, but "French" and "English" are because they refer to specific languages that are proper nouns.

In summary, "Sunday" is capitalized because it is a proper noun that refers to a specific day named after the Sun. The capitalization of days of the week, months, and other similar terms is a reflection of their status as proper nouns in the English language, which is a convention that has been established through historical usage and grammatical rules.

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Months (January, February) and days of the week (Sunday, Monday) are also treated as proper nouns. Seasons and the numbers of the days of the months are not. Also, names of school subjects (math, algebra, geology, psychology) are not capitalized, with the exception of the names of languages (French, English).read more >>