A wine bottle of about six times the standard size.
Origin
Late 19th century: from the name Rehoboam.
Rehoboam2
/ˌriːəˈbəʊəm /
Son of Solomon, king of ancient Israel circa 930-circa 915 bc. His reign witnessed the secession of the northern tribes and their establishment of a new kingdom under Jeroboam, leaving Rehoboam as the first king of Judah (1 Kings 11-14).