underpin

verb

un·​der·​pin ˌən-dər-ˈpin 

underpinned; underpinning; underpins

transitive verb

1

: support, substantiate

underpin a thesis with evidence

2

: to form part of, strengthen, or replace the foundation of

underpin a structure

underpin a sagging building

Synonyms of underpin

• sustain
• carry
• support
• bolster

Examples of underpin in a Sentence

a wall underpinned by metal beams

the central beliefs that underpin a free society

Recent Examples on the Web

Quantum computing is increasing the urgency of replacing cryptographic algorithms that have protected digital systems for decades, including algorithms that underpin public key infrastructure. — Evgeny Gervis, Forbes.com, 22 Sep. 2026

Nearly $2 billion from venture capital investors has underpinned Zipline’s global business that has grown from flying medical supplies to food delivery for Uber. — Alexander Onukwue, semafor.com, 22 Sep. 2026

That theory underpinned the bill, but Newsom warned that proceeding before federal courts established its legality was a risk. — Jaweed Kaleem, Los Angeles Times, 21 Sep. 2026

Even as so many families rely on the bus for their kids to get an education, most of the legal agreements underpinning the city’s school transportation system have not been modernized in decades. — Cayla Bamberger, New York Daily News, 18 Sep. 2026

Word History

First Known Use

1522, in the meaning defined at sense 1

Rhymes for underpin

• aneurin
• crystallin
• eosin
• mandolin
• porphyrin
• superfine
• vietminh
• violin
• akin
• auxin
• buckskin
• chagrin

Kids Definition

underpin

verb

un·​der·​pin -ˈpin 

1

: to give support to

underpin an argument with evidence

2

: to form part of, strengthen, or replace the foundation of

underpin a structure