The word “pinnacle” refers to the highest point or peak of something, either literally (a high pointed top or peak, such as a mountain or architectural ornament) or figuratively (the culmination or peak of achievement, success, or importance). In common usage, it often describes the ultimate high point in a career, a project, or a field. Key senses:

• Literal peak or point: the top of a mountain or a pointed architectural ornament on buildings.
• Figurative peak: the apex of achievement, power, or success (e.g., “the pinnacle of her career”).
• Architecture: a slender tower or spire-like ornament on a building’s peak or ridge.

Usage tips:

• Usually used in the singular form: “the pinnacle of his career.”
• Can be paired with “of” to specify what is being peaked: “the pinnacle of professional achievement.”

If you’d like, I can provide example sentences or check nuance differences between “pinnacle” and related terms like “apex,” “summit,” or “zenith.”