milestone

From mile +‎ stone. Compare Dutch mijlsteen (“milestone”), German Low German Mielensteen (“milestone”), German Meilenstein (“milestone”), Swedish milsten (“milestone”).

• IPA^(key): /ˈmaɪlstəʊn/

• Audio (Southern England)

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milestone (plural milestones)

1. A stone milepost (or by extension in other materials), one of a series of numbered markers placed along a road at regular intervals, typically at the side of the road or in a median.
2. (idiomatic) An important event in a person's life or career, in the history of a nation, in the life of some project, etc.
   • 1933, Stephen Spender, The Funeral:

     Death is another milestone on their way.

   • 2012 March-April, Terrence J. Sejnowski, “Well-connected Brains”, in American Scientist‎, volume 100, number 2, archived from the original on 27 April 2017, page 171:

     Creating a complete map of the human connectome would therefore be a monumental milestone but not the end of the journey to understanding how our brains work.

   • 2021 October 20, “Stop & Examine”, in RAIL, number 942, page 71:

     She bought the model as a surprise gift for a friend who is a lifelong HST fan and railwayman, and who will soon be celebrating a milestone birthday.

• landmark

• mileage
• milemark
• milemarker
• milepole
• milepost

milestone (third-person singular simple present milestones, present participle milestoning, simple past and past participle milestoned)

1. To place milestones along (a road, etc.).
2. (idiomatic) To plan out a project as a series of major steps.

• lemoniest, lime-stone, limestone