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 of unsound

• sick
• poorly
• bad
• ill
• unhealthy

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

None of this sounds basically unsound. — Erik Sherman, Forbes.com, 20 June 2026

Public schools have always been the one institution that has no option but to work through both sound and unsound choices of our society and our leaders. — Baltimore Sun Staff, Baltimore Sun, 20 May 2026

What is deeply concerning is that the District Attorney is choosing to proceed on a case that is fundamentally unsound and cannot be proven at trial. — ABC News, 2 Apr. 2026

This not only makes the shade problem worse, Chamberlain says, but makes the tree more structurally unsound and vulnerable to damage in harsh weather conditions. — Peg Aloi, The Spruce, 30 Mar. 2026

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