Questions & Answers about Dimanĉo estas mia plej trankvila tago.
In Esperanto, names of the days of the week are usually treated like general nouns for “Monday, Tuesday, …” etc., and when you speak about them in a general sense, you normally don’t use la:
- Dimanĉo estas mia plej trankvila tago. – Sunday is my calmest day (in general).
- Lundo estas labortago. – Monday is a workday.
You would add la only if you mean a specific Sunday:
- La dimanĉo post Kristnasko estis tre trankvila. – The Sunday after Christmas was very calm.
Here, we’re talking about “Sunday” in general, so no article is needed.
It’s capitalized here mainly because it is the first word of the sentence.
In modern Esperanto usage, names of the days of the week are usually written with a lowercase letter when they appear in the middle of a sentence:
- Mi laboras lunde. – I work on Monday(s).
- Dimanĉo estas mia plej trankvila tago. – At the beginning of a sentence, it’s capitalized anyway.
So you’ll mostly see lundo, mardo, merkredo, … in the middle of sentences, and capitalized only at sentence start or in titles.