Easton's Dictionary
Rainy, the eighth ecclesiastical month of the year (1 Kings 6:38), and the second month of the civil year; later called
Marchesvan (q.v.). (See MONTH.)
International Standard Bible Encyclopedia
bul (bul): Name of the 8th month of the Jewish year (1Ki 6:38). It is of Phoenician origin and signifies the month of rain, the beginning of the rainy season.
See CALENDAR.