Cruck

A sturdy timber with a curve or angle used for primary framing of a timber house, usually used in pairs.

"1952: To construct such a house, it is necessary to select an oak with a branch growing out at an angle of about 45°; the upper part of the tree, above the fork, having been cut off, the trunk and branch are roughly squared and divided in half . If the two halves are then placed opposite one another, with the branch ends pegged together, they constitute what was usually known as a 'cruck' or, more correctly, 'a pair of crucks'. — L.F. Salzman, Building in England, p. 195."

To make lame.