Invalid and Illegitimate

Invalid

Invalid adjective - Not using or following good reasoning.
Usage example: an argument which has one untrue premise is invalid

Illegitimate is a synonym for invalid. In some cases you can use "Illegitimate" instead an adjective "Invalid".

Illegitimate

Illegitimate adjective - Not using or following good reasoning.
Usage example: made several illegitimate inferences

Invalid is a synonym for illegitimate in incorrect topic. You can use "Invalid" instead an adjective "Illegitimate", if it concerns topics such as not legal.

Nearby Words: illegitimacy, illegitimately
Cite this Source
Illegitimate and Invalid. (2016). Retrieved 2026, August 13, from https://thesaurus.plus/related/invalid/illegitimate
Invalid & Illegitimate. N.p., 2016. Web. 13 Aug. 2026. <https://thesaurus.plus/related/invalid/illegitimate>.
Illegitimate or Invalid. 2016. Accessed August 13, 2026. https://thesaurus.plus/related/invalid/illegitimate.
Google Ngram Viewer shows how "invalid" and "illegitimate" have occurred on timeline