belief or doubt; truth or error; authenticity
Abstract noun referring to the dichotomy between believing and doubting, or truth and falsehood. Often used in philosophical or formal contexts to discuss credibility, authenticity, or the balance between trust and skepticism.
It is difficult to judge the credibility of that testimony.
The authenticity of historical documents should always be questioned.
Compound of 信 (しん, 'belief') and 疑 (ぎ, 'doubt'), likely coined in Japanese from classical Chinese elements. The exact historical derivation is uncertain.