reef
UK[riːf]US[riːf]
n
A long line of rocks or sand near the surface of the sea, often dangerous to ships.
n
A part of a sail that can be tied or rolled up to reduce its area.
Etymology
The word 'reef' entered English from two distinct but possibly related Old Norse sources. The nautical sense of a ridge of rock or sand derives from Old Norse 'rif', meaning 'rib' or 'reef', a metaphor comparing the underwater ridge to the ribs of a body. The sailing term for reducing a sail's area comes from Old Norse 'rif', meaning 'a strip or a reef in a sail'. Both senses were adopted into Middle Dutch as 'rif' and subsequently into Middle English, where they converged into the single spelling 'reef'. The underlying logic connects the idea of a raised, linear structure—whether a skeletal rib or a folded strip of cloth—to the modern specialized meanings in maritime contexts.
Analysis
The word 'reef' is a simplex word of Old Norse origin, borrowed into Middle English. It does not contain separable morphemes in its modern English form.
Examples
The ship was wrecked on a coral reef.
The sailors had to reef the mainsail quickly as the storm approached.
The Great Barrier Reef is the world's largest coral reef system.