Crowning describes the achievement that stands at the very top of a life's work. Her crowning achievement, the crowning glory, a crowning moment.
It marks the last and greatest of a series, which is why it goes with achievement and glory rather than with a first success. Crowning glory is also used of somebody's hair, which is a quite separate and slightly arch use. In childbirth, crowning is the moment the head first appears, which is a precise clinical term.
1adjectivecrowningStanding at the top of a life's achievements.
“Winning the Olympic gold was the crowning achievement of her long career.”
2nounmomentThe moment in childbirth when the head first appears.
“During crowning, the midwife told her to stop pushing and breathe slowly.”
crowning is a quality of culmination.
Crown plus -ing, from Latin corona, a wreath. The metaphor is the coronation itself — the thing placed last and highest.
Middle English
crowninge
English, today
crowning
From Middle English crowninge, crounende, equivalent to crown + -ing.
Etymology from Wiktionary, CC BY-SA