undeceivable
Immune to lies
Undeceivable describes someone who cannot be fooled or misled.
The word implies a person of such sharp discernment or firm conviction that deception simply won't work on them: She proved undeceivable—every lie he told, she saw through instantly.
The term is rare and somewhat formal, appearing mostly in philosophical or religious contexts about truth-seeking.
Mentally sharp, discerning
- shrewdPractically clever, perceptive
- discerningHaving keen judgment
- keenSharp or enthusiastic
- sharpFine-edged, or astute
insightful · penetrating · perspicacious · clear-sighted · observant · sharp-eyed · quick-witted · savvy
Uncertain of truth
- questioningSeeking answers through inquiry
- suspiciousInclined to distrust
- incredulousExpressing unwillingness to believe
- waryGuardedly alert
unconvinced · distrustful · leery · cynical · scrutinizing · critical · guarded · cautious
Firmly loyal, unshakeable
- resoluteFixed in purpose
- unwaveringSteady and unchanging
- principledHaving strong moral beliefs
- uprightVertical or morally sound
honest · true · faithful · unbribable · firm · unmovable · constant · loyal
astute
Mentally sharp, discerning
- shrewdPractically clever, perceptive
- discerningHaving keen judgment
- keenSharp or enthusiastic
sharp · insightful · penetrating · perspicacious · clear-sighted · observant · sharp-eyed · quick-witted · savvy · canny
doubtful
Uncertain of truth
- questioningSeeking answers through inquiry
- suspiciousInclined to distrust
- incredulousExpressing unwillingness to believe
wary · unconvinced · distrustful · leery · cynical · scrutinizing · critical · guarded · cautious · disbelieving
steadfast
Firmly loyal, unshakeable
- resoluteFixed in purpose
- unwaveringSteady and unchanging
- principledHaving strong moral beliefs
upright · honest · true · faithful · unbribable · firm · unmovable · constant · loyal · honorable
undeceivabledeceivable
Able to be tricked
gullible · credulous · naive · easily fooled · suggestible
deception, deceive, deceit, deceptive, deceitful, deceiver, deceptively, undeceive, deceptiveness