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

As classic cars prepare to roll onto the Mother Road and communities across eight states launch centennial celebrations, organizers hope the milestone serves not only as a tribute to history but as a call to preserve what comes next. —Daily News, 9 June 2026

That's a huge milestone and a special moment. —Patrick Saunders, Denver Post, 8 June 2026

Even a milestone like a 35th launch and landing, bringing it closer to space shuttle Discovery‘s record of 39 spaceflights across nearly four decades, seems hardly worth mentioning. —Eric Berger, ArsTechnica, 8 June 2026

Shaboozey’s milestone Grammy victory happened to fall on the first day of Black History Month. —Joseph Hudak, Rolling Stone, 8 June 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