thalweg or talweg /tälˈveg, -vāhh/ (geology)

1. The longitudinal profile of the bottom of a river bed
2. The middle of a main navigable waterway, acting as a boundary between states

• orology
• oropesa
• oropesas
• oropharynx
• oropharynxes
• ororotund
• ororotundities
• ororotundity
• or otherwise
• orotund
• orotundities
• orotundity
• orphan
• orphanage
• orphanages
• orphan-asylum
• orphan-asylums
• orphan disease
• orphaned
• orphanhood
• orphanhoods
• orphaning
• orphanism
• orphanisms
• orphans