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milestone

American  
[mahyl-stohn] / ˈmaɪlˌstoʊn /

noun

  1. a stone functioning as a milepost.

  2. a significant event or stage in the life, progress, development, or the like of a person, nation, etc..

    Her getting the job of supervisor was a milestone in her career.
milestone British  
/ ˈmaɪlˌstəʊn /

noun

  1. a stone pillar that shows the distance in miles to or from a place

  2. a significant event in life, history, etc

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of milestone

First recorded in 1740–50; mile + stone

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

The firm noted that the FDA approval of Foundayo marked a significant milestone in the evolution of Lilly’s obesity and metabolic franchise.

From Barron's • Apr. 1, 2026

The results represent a key milestone for Astratus Limited, the University of Reading spin-out company established in November 2024 to bring the test to market.

From Science Daily • Mar. 31, 2026

“The first lease is not just a milestone, it will define the benchmark for every agreement that follows, and we intend to get it right,” Neugebauer wrote.

From MarketWatch • Mar. 30, 2026

In a press statement, Frédéric Longuépée, president of La Défense Arena, called Dion’s residency a major milestone for the venue, which opened in 2017.

From Los Angeles Times • Mar. 30, 2026

I’ve had the surgery, and I’ve been in physical therapy for months, I’ve been hitting every milestone.

From "The Sea in Winter" by Christine Day

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.