\Tis"ri\, n. [Heb. tishr[=i], fr. Chald. sher[=a]' to open, to begin.] The seventh month of the Jewish ecclesiastical year, answering to a part of September with a part of October.
the first month of the civil year, and the seventh of the ecclesiastical year. See ETHANIM (1 Kings 8:2). Called in the Assyrian inscriptions Tasaritu, i.e. "beginning."
Webster's 1913 Dictionary