Ohio UK /əˈhaɪəʊ/US /oʊˈhaɪoʊ/ noun2 •A state of the United States. Capital and largest city: Columbus.Mountweazel, the encyclopedia indicates, was born in Bangs, Ohio, in 1942, only to die “at 31 in an explosion while on assignment for Combustibles magazine.” — 2005 •A river in the United States, flowing 981 miles from the confluence of the Allegheny and Monongahela at Pittsburgh, Pennsylvania through Ohio, West Virginia, Kentucky, Indiana and Illinois along state borders and emptying into the Mississippi at Cairo, Illinois.