n. (Mach.) A beam or bar across the head or end of a rod, etc., or a block attached to it and carrying a knuckle pin; as the solid crosspiece running between parallel slides, which receives motion from the piston of a steam engine and imparts it to the connecting rod, which is hinged to the crosshead. [ 1913 Webster ]

n. a heading of a subsection printed within the body of the text.
Syn. -- crosshead. [ WordNet 1.5 ]