cocket center

noun or cocket centering

Etymology: obsolete English cocket to mortise, join, from Italian cocchetta, diminutive of cocca notch, knot, probably from Latin coccum excrescence on a tree, berry of the scarlet oak — more at coak

: an arch center or centering in which the horizontal tie beam is replaced by bracing that allows headway above the springers to permit passage through while building