Easton's Dictionary
A Persian word (Assyr, sivanu, “bricks”), used after the
Captivity as the name of the third month of the Jewish year,
extending from the new moon in June to the new moon in July
(Esther 8:9).
International Standard Bible Encyclopedia
se-van', si'-van (ciwan): The third month of the Jewish year, corresponding to June (Es 8:9).
See CALENDAR.