(US) A short-handled sledgehammer used with one hand, with a head weighing 3-4 pounds and two flat faces.

(US) A long-handled sledgehammer used with both hands

plural of single jack

plural of double jack

plural of Cousin Jack

(slang, dated) A Cornishman.

An arch of the thickness of one brick.

(UK) One of the shorter rafters used in constructing a hip or valley roof.

(nautical) A block fixed in the topgallant or royal rigging, used for raising and lowering light masts and spars.

In a hip roof, a minor truss used where the roof does not have its full section.