Simple past tense and past participle of reef.(verb)
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Use "reefed" in a sentence
"Hidden by them, he sat up and reefed the sail, then looked back for the last time at the perimeter of the lagoon."
"The public space is a six-floor-high atrium that occupies the center of the building, with a gigantic metal-fabric drapery, which I thought of as a loosely reefed sail."
"He reefed hastily to the uttermost, and at the same time depressed the angle of his flight to meet that upward surge."