The word 'zenithal' is a modern English formation that combines the noun 'zenith' with the adjectival suffix '-al'. The core term 'zenith' has a fascinating journey, entering European astronomy via Medieval Latin translations of Arabic texts. The Arabic term 'samt' (path) was misread as 'cenit', which later evolved into the English 'zenith', specifically denoting the point in the sky directly overhead. By adding the Latin-derived suffix '-al', meaning 'pertaining to', the word 'zenithal' was created to describe anything relating to this highest celestial point, a meaning easily extended to figurative peaks or culminations. Thus, the term logically builds from a concept of a supreme directional point to describe a state of being at the apex.

Structure: zenith + al - zenith: From Medieval Latin 'cenit', a scribal error for Arabic 'samt' (path, direction), specifically 'samt ar-ras' (path over the head). In English, it denotes the highest point in the celestial sphere. - al: A suffix of Latin origin ('-alis'), used to form adjectives meaning 'of, relating to, or characterized by'.