cardo

Uncertain. Traditionally related to Ancient Greek κράδη (krádē, “twig, spray; swing, crane in the drama”), but unlikely as the concordant sense of swing is metaphorical and likely too recent. Or from Proto-Indo-European *(s)kerd- (“to move, sway, swing, jump”) and so cognate with Proto-Germanic *herzô (“bar, pivot, hinge”) (whence English har (“hinge”)). Compare in any case Old High German scerdo (“hinge”).