unsound

adjective

un·​sound ˌən-ˈsau̇nd 

: not sound: such as

a

: not healthy or whole

an unsound horse

b

: not mentally normal : not wholly sane

of unsound mind

c

: not firmly made, placed, or fixed

structurally unsound

d

: not valid or true : invalid, specious

unsound beliefs

unsoundly

ˌən-ˈsau̇n(d)-lē 

adverb

Synonyms

• sick
• poorly
• bad
• ill
• unhealthy
• shaky

Examples of unsound in a Sentence

The roof is structurally unsound.

disgruntled relatives tried to prove that the woman was of unsound mind when she made her will

Recent Examples on the Web

This could spell further trouble for the Premier League, opening them up to the argument and possible legal claim that clubs were materially disadvantaged by unsound regulations. —Jacob Whitehead, New York Times, 15 Aug. 2025

Former President Sall dismissed the audits as technically unsound, but the announcement of nearly a quarter of GDP in unreported debt embarrassed the IMF and World Bank. —Joël Té-Léssia Assoko, semafor.com, 25 July 2025

The chances are solid that some portion of the time, the AI will be emitting remarks and instructions that are unsound. —Lance Eliot, Forbes.com, 11 July 2025

But don’t get too attached to any of these morally unsound characters, since all are mere bait for this killer. —Randy Myers, Mercury News, 20 June 2025

Word History

First Known Use

14th century, in the meaning defined above

Phrases Containing unsound

• of unsound mind

Rhymes for unsound

• abound
• aground
• around
• astound
• background
• campground
• clothbound
• confound
• earthbound
• eastbound
• expound
• fairground

Kids Definition

unsound

adjective

un·​sound ˌən-ˈsau̇nd 

ˈən-

1

: not healthy or whole

an unsound horse

2

: not mentally normal : not wholly sane

of unsound mind

3

: not firmly made, placed, or fixed

an unsound structure

4

: not based on truth or logic

unsound arguments

unsoundly

-ˈsau̇n-(d)lē 

adverb

unsoundness

-ˈsau̇n(d)-nəs

noun

Medical Definition

unsound

adjective

un·​sound -ˈsau̇nd 

: not sound: as

a

: not healthy or whole

an unsound limb

an unsound horse

b

: not mentally normal : not wholly sane

of unsound mind

c

: not fit to be eaten

unsound food

unsoundness noun

Legal Definition

unsound

adjective

un·​sound ˌən-ˈsau̇nd 

: not sound: as

a

: not healthy or whole

b

: not mentally normal : not wholly sane

of unsound mind

c

: not firmly made, placed, or fixed

d

: not valid or true

an unsound argument

unsoundly adverb

unsoundness noun