«فَإِنْ خُولِفَ بِرَاجِحٍ مِنْهُ ... فَالرَّاجِحُ يُقَالُ لَهُ: الْمَحْفُوظُ، وَمُقَابِلُهُ ... الشَّاذُّ»
Where an otherwise acceptable narrator is contradicted by a better-supported version, the preferred version is called mahfuz and the inferior conflicting version shadh.
Mahfuz is the better-preserved account in that particular comparison. Shadh in this technical formulation is not simply “an unusual report,” but an accepted narrator's conflicting account that loses against stronger evidence.
A solitary narration is therefore not automatically shadh. Reliable uniqueness can coexist with acceptance where no disqualifying conflict has been established.