1Tuesday, the day of the week after Monday. A shortened form of 火曜日 (kayōbi), commonly used in speech, calendars, and casual writing.
火曜は病院が休みです。
The hospital is closed on Tuesdays.
火曜までにこの本を返してください。
Please return this book by Tuesday.
次の火曜、一緒にご飯を食べに行かない？
Want to go get a meal together next Tuesday?