open bar

noun

a bar at a reception that serves drinks whose cost has been borne by the host, an admission charge, a sponsor, etc.: Before the banquet there will be an open bar from 5 to 7 p.m.
Compare cash bar.

Origin of open bar

First recorded in 1970–75

Words nearby open bar

open admissions, open adoption, open air, open and aboveboard, open and shut, open bar, open biopsy, open bite, open book, open brethren, open call