[ze.nith] n [ME senith, fr. MF cenith, fr. ML, fr. OSp zenit, modif. of Ar samt (ar-ra's) way (over one's head)] (14c) 1: the point of the celestial sphere that is directly opposite the nadir and vertically above the observer
2: the highest point reached in the heavens by a celestial body
3: culminating point: acme "at the ~ of his powers --John Buchan"