Invalid
Invalid adjective - Having no cogency or legal force.
Usage example: invalid reasoning
Legitimate is an antonym for invalid.
Legitimate
Legitimate adjective - Of marriages and offspring; recognized as lawful.
Both words in one sentence
- This fallacy differs from reductio ad absurdum, a legitimate debating technique; there, it is demonstrated that an absurd conclusion naturally follows from the underlying logic of an opponent's argument, therefore showing the argument as invalid.
Source: Appeal to Ridicule -
The Gage Historical pack update also caused a lot of false positives to occur by branding legitimate players as cheaters for having an invalid weapon (despite the fact that they purchased the DLC), causing many paranoid players to start kicking out people the minute the cheater tag appears.
Source: Video Game / PAYDAY 2
Cite this Source
Legitimate and Invalid. (2016). Retrieved 2026, July 21, from https://thesaurus.plus/related/invalid/legitimate
Invalid & Legitimate. N.p., 2016. Web. 21 Jul. 2026. <https://thesaurus.plus/related/invalid/legitimate>.
Legitimate or Invalid. 2016. Accessed July 21, 2026. https://thesaurus.plus/related/invalid/legitimate.
Google Ngram Viewer shows how "invalid" and "legitimate" have occurred on timeline