Rational
Rational adjective - According to the rules of logic.
Usage example: insisted there was a rational explanation for the strange creaking noises and that there were no such things as ghosts
Sound is a synonym for rational in sensible topic. In some cases you can use "Sound" instead the word "Rational" as an adjective or a noun, when it comes to topics like behaviour, character trait, reason, sane. popular alternative
Sound
Sound adjective - According to the rules of logic.
Usage example: sound reasoning alone should tell you that the result is invalid
Rational is a synonym for sound in sensible topic. You can use "Rational" instead an adjective "Sound", if it concerns topics such as behaviour, mental condition, reason, sane. popular alternative
Mutual synonyms
Both words in one sentence
- No matter how rational Stan's ideas sound, they're all doomed to failure simply because he thought them up.
Source: Unwanted Assistance -
Expy: Mike's backstory (as revealed in the Season 2 premiere) makes him sound a little like Batman if Bruce made more rational decisions.
Source: Series / Suits - It may sound like a rational thing to do since by definition a fallacious argument makes no sense, and this rule may seem like a mindscrewy special case, but...
Source: Fallacy Fallacy
Cite this Source
Sound and Rational. (2016). Retrieved 2026, July 21, from https://thesaurus.plus/related/rational/sound
Rational & Sound. N.p., 2016. Web. 21 Jul. 2026. <https://thesaurus.plus/related/rational/sound>.
Sound or Rational. 2016. Accessed July 21, 2026. https://thesaurus.plus/related/rational/sound.
Google Ngram Viewer shows how "rational" and "sound" have occurred on timeline