The Collaborative International Dictionary
Bed screw
Bed screw \Bed" screw`\
(Naut.) A form of jack screw for lifting large bodies, and assisting in launching.
A long screw formerly used to fasten a bedpost to one of the adjacent side pieces.
Wiktionary
bed screw
n. 1 (context nautical English) A form of jack screw for lifting large bodies and assisting in launching. 2 A long screw formerly used to fasten a bedpost to one of the adjacent side pieces.