means The highest point of something — the peak of achievement, success, or physical height.

from From Latin 'pinnaculum,' a little wing or gable, the diminutive of 'pinna' (wing, feather, or pointed peak). It traveled through Old French as 'pinacle' before settling into English, where it first named the soaring spires and turrets that crowned cathedrals — those topmost points reaching toward heaven. From architecture it climbed into metaphor, becoming any summit at all.