mac·​ad·​am mə-ˈka-dəm How to pronounce macadam (audio)
: macadamized roadway or pavement especially with a bituminous binder

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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 examples are programmatically compiled from various online sources to illustrate current usage of the word 'macadam.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


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

First Known Use

1824, in the meaning defined above

Time Traveler
The first known use of macadam was in 1824


Dictionary Entries Near macadam

Cite this Entry

“Macadam.” Dictionary, Merriam-Webster, Accessed 4 Oct. 2023.

Kids Definition


mac·​ad·​am mə-ˈkad-əm How to pronounce macadam (audio)
: a roadway or pavement constructed by compacting a layer of small broken stone along with a binder (as cement or asphalt)

named for John L. McAdam 1756–1836 Scottish engineer who invented the paving process

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