A high point: the highest point of any range, the most developed stage of any process, or the culmination of any field or historical period.
A paragon: a person or thing representing such a high point.
Synonym of crisis, the decisive moment in the course of an illness.
Full bloom or reproductive maturity.
Ideal excellence, or an imaginary standard of perfection.
An emulable eidolon embodying excellence in a particular respect.