noun, adverb
The day of the week. Can be used as a noun or adverbially (e.g., 日曜日に, 日曜日は).
日曜日はいつも家族と過ごします。
I always spend Sundays with my family.
次の日曜日に会いましょう。
Let's meet next Sunday.
Abbreviation of 日曜日, commonly used in schedules and compound words (e.g., 日曜朝, 日曜日). Slightly more casual or abbreviated feel.
Compound of 日 (sun, day) + 曜 (day of the week) + 日 (day). The reading にちようび is the standard Sino-Japanese reading of the characters.