Definitions

unsound

[uhn-sound] / ʌnˈsaʊnd /

ADJECTIVE

not well; flimsy

Synonyms

STRONGEST

defective erroneous false faulty flawed fragile illogical inaccurate incorrect insane insecure shaky unbalanced unhealthy unreliable unsafe unstable

WEAK

ailing crazed dangerous decrepit delicate demented deranged diseased fallacious frail ill in poor health incongruous infirm insubstantial invalid lunatic mad not solid rickety specious tottering unbacked unhinged unsteady unsubstantial unwell weak wobbly

Antonyms

STRONGEST

accurate balanced certain correct firm healthy honest just perfect protected rational reasonable reliable right safe sane secure sound stable steady strong sure true valid well

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Germany is uniquely neurotic about debt and about unsound money.

From BBC • Mar. 27, 2026

She’s right about that, but this manual included some unsound science.

From The Wall Street Journal • Feb. 8, 2026

That assessment was technically accurate but fundamentally unsound.

From Slate • Mar. 28, 2025

The surface pleasures of “Y2K” are outlandishly fun, but plot-wise, the film is structurally unsound.

From Los Angeles Times • Dec. 6, 2024

Although swidden does permit the forest to regrow, it is wildly inefficient and environmentally unsound.

From "1491" by Charles C. Mann