object lesson

American  

noun

1. a practical or concrete illustration of a principle.

---

object lesson British  

noun

1. a convincing demonstration of some principle or ideal

2. (esp formerly) a lesson in which a material object forms the basis of the teaching and is available to be inspected

---

Etymology

Origin of object lesson

First recorded in 1825–35

Example Sentences

Industry insiders have told the BBC that Fishwick is now regarded as an object lesson in how not to run an installation project.

From BBC • Oct. 30, 2025

That’s the bigger story that is being lost in the government’s egregious, ham-handed attempt to turn Ábrego García into an object lesson.

From Salon • Jul. 17, 2025

South Carolina State Conference of the NAACP, is an object lesson in the conflict between two competing theories of how we should think about racism in America today.

From Seattle Times • May 28, 2024

Though he may be referring to setbacks in his gubernatorial career, such a position does not transfer easily across to Schwarzenegger’s personal conduct down the years, which has scarcely been an object lesson in integrity.

From Los Angeles Times • Oct. 6, 2023

Nevertheless, the Burr-Hamilton duel helped turn the tide against the practice of dueling by providing a focal point for its critics and serving as a dramatic object lesson of its self-destructive character.

From "Founding Brothers: The Revolutionary Generation" by Joseph J. Ellis