milestone

noun

mile·​stone ˈmī(-ə)l-ˌstōn 

1

: a stone serving as a milepost (see milepost sense 1)

2

: a significant point in development

Graduating from college was an important milestone in her life.

Illustration of milestone

• milestone 1

Synonyms of milestone

• climax
• landmark
• watershed
• corner

Examples of milestone in a Sentence

the new drug was regarded as a milestone in the treatment of heart disease

Recent Examples on the Web

For the five-year anniversary, Alves took to Instagram to share what the milestone meant to her. — Janelle Ash, FOXNews.com, 4 July 2026

Chapman allowed back-to-back singles after his milestone strikeout, but got Jo Adell to ground into a double play to secure his 17th save. — ABC News, 4 July 2026

Then, eight months ago, the president created called Freedom 250 to carry out his vision for the milestone anniversary. — Karissa Waddick, USA Today, 4 July 2026

This special edition rocket was designed for the once-in-a-lifetime milestone of 250 years of American independence. — Harry Bennett, Space.com, 3 July 2026

Word History

First Known Use

1662, in the meaning defined at sense 1

Rhymes for milestone

• acetone
• anglophone
• baritone
• bourguignon
• buspirone
• chaperon
• chaperone
• cobblestone
• collarbone
• cornerstone
• cortisone
• dictaphone

Kids Definition

milestone

noun

mile·​stone ˈmī(ə)l-ˌstōn 

1

: a milepost made of stone

2

: an important point in progress or development