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

• spiral fractures
• spiral galaxies
• spiral galaxy
• spiraliform
• spiralism
• spiralisms
• spiralist
• spiralists
• spiralities
• spirality
• spiralled
• spiralling
• spirally
• spiral ratchet screwdriver
• spiral ratchet screwdrivers
• spirals
• spiral staircase
• spiral staircases
• spirant
• spirants
• spiraster
• spirasters
• spirated
• spiration
• spirations