knuckle timbern. a timber having or forming a knuckle (see 4c).
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1711 W. SutherlandShip-builders Assistant 54 The Planks under the Nuckle Timbers forward.
1850 J. GreenwoodSailor's Sea-bk. 128Knuckle-timbers, those top~timbers in the fore body whose heads stand perpendicular, and form an angle with the hollow of the topside.