pinnacle
UK[ˈpɪnək(ə)l]US[ˈpɪnək(ə)l]
n
The most successful point; the culmination.
n
A high, pointed piece of rock.
n
A small ornamental turret or spire on a roof.
Etymology
The journey of 'pinnacle' begins with the Latin word pinna, which originally meant "feather" but, by metaphorical extension, came to signify a "battlement" or "parapet" due to the projecting, wing-like shape of fortifications. The diminutive form pinnaculum thus meant "a small wing or turret." This term passed into Old French as pinacle, referring specifically to a slender architectural peak. Entering English in the 14th century, its meaning expanded from the literal architectural spire to metaphorically represent the highest point of achievement or development, perfectly capturing the sense of being at a supreme and often precarious summit.
Analysis
The word 'pinnacle' is a simplex form borrowed as a whole from Old French. Its ultimate Latin root is pinnaculum, a diminutive of pinna, meaning "feather, wing, battlement".
Examples
She reached the pinnacle of her career when she was appointed CEO.
The climbers struggled to reach the rocky pinnacle.
The cathedral's pinnacles were beautifully outlined against the sky.