object lesson

American  

noun

1. a practical or concrete illustration of a principle.

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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

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Etymology

Origin of object lesson

First recorded in 1825–35

Example Sentences

In the Middle Ages, the French disaster at Crécy became an object lesson in the dangers of rushing in.

From Slate • Apr. 13, 2026

He and his representatives are now threatening Cuba, Mexico, Colombia, Iran and Greenland, with Venezuela serving as an object lesson of what may happen if a country dares to disobey his wishes.

From Salon • Jan. 6, 2026

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

As the kids grew older, she said, the business became a source of pride, and an object lesson in loyalty, endurance.

From Seattle Times • Feb. 16, 2024

The incredible effort of moving the boy to Boston, then watching him die, later struck me as an object lesson in the difficulty of Farmer’s mission, perhaps in its ultimate futility.

From "Mountains Beyond Mountains" by Tracy Kidder and Michael French