'apex' originates from Latin, specifically the word 'apex', where it meant 'summit, peak, tip'.

'apex' was used in Classical and Medieval Latin with the same form 'apex'; it entered English from Latin (via Medieval/Low Latin and through scholarly or literary borrowing) and became the modern English word 'apex'.

Initially, it meant 'summit, tip' in Latin; over time it retained that core sense and extended to figurative uses such as the 'highest point' of events or conditions, and then developed verbal uses (to apex = to reach a highest point).