noun
Nautical term for a rope used to secure a boat to a dock or another vessel. The word is somewhat specialized but known in boating contexts.
船を岸壁に舫いで固定した。
We secured the boat to the quay with a mooring rope.
舫いが切れて船が流された。
The painter broke and the boat drifted away.
Derived from the verb 舫う (もやう), meaning 'to moor' or 'to tie up a boat'. The noun form 舫い refers to the rope used for that purpose.