billabong /bilˈə-bong/ (Aust)

1. A cut-off loop of a river, replenished only by floods
2. An offshoot from a river (strictly one that does not rejoin it)

• orthros
• orthroses
• ortolan
• ortolans
• orts
• orval
• orvals
• Orvietan
• Orvieto
• Orwellian
• or whatever
• or whenever
• or wherever
• oryctologies
• oryctology
• oryx
• oryxes
• Oryza
• orzo
• orzos
• os
• O's
• OS
• Os
• OSA