Sivan (Hebrew: סִיוָן, Modern: Sivan, Tiberian: Siwān, from Akkadian simānu, meaning "season; time") is the ninth month of the civil year and the third month of the religious year on the Hebrew calendar. It is a month of 30 days. Sivan usually falls in May–June on the Gregorian calendar. Along with all other current, post-biblical Jewish month names, Sivan was adopted during the Babylonian captivity. In the Babylonian calendar it was named Araḫ Simanu. Holidays. 6–7 Sivan – Shavuot. In Jewish history.
https://en.wikipedia.org/wiki/Sivan