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

One future milestone for SpaceX will be to not only carry out an orbital flight, but to return both the Super Heavy and the Starship to the launch site and capture them on the tower that launched them. — New Atlas, 29 Sep. 2026

When clients or surrogates travel to California for important medical milestones, Tang and Sonnenberg are often there themselves—arranging schedules, accompanying appointments, and ensuring that days defined by medicine retain a sense of humanity. — Robb Report Studio, Robb Report, 29 Sep. 2026

Despite a valiant effort on the water, that milestone failed to normalize a more ever-present female presence at the Cup for almost three decades. — Stefano Pozzebon, CNN Money, 28 Sep. 2026

While the ratings and programming landscape has changed dramatically over the intervening decades, this year’s playoffs (starting Tuesday) are shaping up as a back-to-the-future milestone for NBC Sports. — Dade Hayes, Deadline, 28 Sep. 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