There doesn't seem to be an English word describing the ability to tell truth from a lie. I've Googled, and posted on my FB account, but can't seem to find a word that precisely describes this ability.
- Discernment. M-W defines this as "able to see and understand people things, or situations clearly and intelligently." Best so far, but a bit off the mark. It does not precisely identify the ability to perceive and separate truth from falsehoods.
- The antonym of gullible
- A discerning ear
- (Slang) anti-bs meter; able to discern bullsh!t.
Others have suggested guarded, prudent, realistic, astute, and perceptive... but none of these precisely describe the quality that I've described.
I don't think that English has a word to describe this! Perhaps something from Latin, Hebrew, or another language?
Tyvm Keith :^)
EDIT per Tonepoet's comment below:
This question is a single-word-request and as such needs to be edited to include a requisite contextual sentence to help us understand what the best word is to meet your needs.
John is so gullible; he'll believe anything. Not so Jane, she is XXXXXXX. She has quite the discerning ear; you'll never be able to deceive her with a lie.
Since you have proposed a synonym/antonym, you should also show us that you have consulted a thesaurus and tell us why you have dismissed at least the very best examples as meeting your needs. The question may end up closed otherwise.
Consulted thesaurus.com. Listed antonyms for
gullible; definitions from Google.
- discerning. Having or showing good judgment. Discussed above; best so far, but a bit off the mark.
- astute. Having or showing an ability to accurately assess situations or people and turn this to one's advantage. Rejected because does not account for lies.
- knowledgeable. intelligent and well informed. Does not speak to distinguishing truth from lies.
- perceptive. Having or showing sensitive insight. Does not speak to discernment of truth or lies.
- suspicious. Having or showing a cautious distrust of someone or something.. Speaks more to distrust than separation of truth from lies.
- unbelieving. Not believing someone or something. Does not speak to the ability to distinguish truth from lies.