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

From concept development to flight qualification The US company and its partners have already passed several development milestones since the program started. — Bojan Stojkovski, Interesting Engineering, 6 Sep. 2026

Italy's economy slows The milestone is particularly notable in a country long associated with political instability — a problem heightened by the 2010 to 2012 euro zone sovereign debt crisis — with 68 governments serving over 80 years. — Jenni Reid,chloe Taylor, CNBC, 5 Sep. 2026

Surging diesel fuel prices hit a milestone as prices slam California’s economy, from trucks to crops. — Andrew J. Campa, Los Angeles Times, 5 Sep. 2026

While Ortiz-Magro celebrates turning 40 with his family, Giancola, 39, is celebrating a milestone of her own. — Lily Brown, PEOPLE, 4 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