mac·​ad·​am | \ mə-ˈka-dəm How to pronounce macadam (audio) \

Definition of macadam

: macadamized roadway or pavement especially with a bituminous binder

John Loudon McAdam and Macadam

In 1783, inventor John Loudon McAdam returned to his native Scotland after amassing a fortune in New York City. He became the road trustee for his district and quickly set his inventiveness to remedying the terrible condition of local roads. After numerous experiments, he created a new road surfacing material made of bits of stone that became compressed into a solid mass as traffic passed over them. His invention revolutionized road construction and transportation, and engineers and the public alike honored him by using his name (respelled macadam) as a generic term for the material or pavement made from it. He is further immortalized in the verb macadamize, which names the process of installing macadam on a road.

Examples of macadam in a Sentence

Recent Examples on the Web Crushed stone or even macadam became the roads’ base. Mary Ann Ashcraft,, 11 Oct. 2019 The macadam on Tenth Street comes out of the winter in wretched condition. Arthur Hart, idahostatesman, 30 June 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'macadam.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of macadam

1824, in the meaning defined above

History and Etymology for macadam

after John Loudon McAdam †1836 Scottish civil engineer who introduced this method of road construction

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The first known use of macadam was in 1824

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Dictionary Entries Near macadam



macadamia nut

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Cite this Entry

“Macadam.” Dictionary, Merriam-Webster, Accessed 16 May. 2022.

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More Definitions for macadam


mac·​ad·​am | \ mə-ˈka-dəm How to pronounce macadam (audio) \

Kids Definition of macadam

: a road surface made of small closely packed broken stone

More from Merriam-Webster on macadam

Nglish: Translation of macadam for Spanish Speakers Encyclopedia article about macadam


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