unsound.

1. Based on faulty reasoning, false premises, or unreliable support.

2. Structurally or physically defective or unfit.

Use it for

Words that belong together

• unsound argument
• unsound conclusion

On the page

The argument is unsound because a necessary premise is false.

Usage notes

Primary category: analysis / argumentation / evidence. Forms: Comparative more unsound; superlative most unsound when comparison is meaningful. Legacy lexical fields mirror sense 1 only. Use numbered sense fields for all meanings. Established modern English lexical item. No separate regional spelling or grammatical inflection entry. Writing functions: evidence, inference, qualification. Commonness: moderately common.