Noun
the keystone of an arch
expandable metal or wooden wedge used by printers to lock up a form within a chase
Source: WordNetFrom high black walls, gleaming vaguely with rain, Each yellow light looked down like a golden eye. They trembled from coign to coign, and tower to tower, Along high terraces quicker than dream they flew. And some of them steadily glowed, and some soon vanished, And some strange shadows threw. Conrad Aiken