Reef builder (Zoöl.), any stony coral which contributes material to the formation of coral reefs. -- Reef heron (Zoöl.), any heron of the genus Demigretta; as, the blue reef heron (D. jugularis) of Australia.

* From the head to the first reef-band, in square sails, is termed the first reef; from this to the next is the second reef; and so on. In fore-and-aft sails, which reef on the foot, the first reef is the lowest part. Totten.

Close reef, the last reef that can be put in. -- Reef band. See Reef-band in the Vocabulary. -- Reef knot, the knot which is used in tying reef pointss. See Illust. under Knot. -- Reef line, a small rope formerly used to reef the courses by being passed spirally round the yard and through the holes of the reef. Totten. -- Reef points, pieces of small rope passing through the eyelet holes of a reef-band, and used reefing the sail. -- Reef tackle, a tackle by which the reef cringles, or rings, of a sail are hauled up to the yard for reefing. Totten. -- To take a reef in, to reduce the size of (a sail) by folding or rolling up a reef, and lashing it to the spar.

To reef the paddles, to move the floats of a paddle wheel toward its center so that they will not dip so deeply.