When describing relative singularity, merely saying “the report is isolated” may be incomplete. It is better to identify the precise student–teacher relationship in which the isolation occurs.
Example 1: “Only N transmitted this report from M” identifies both sides of the relationship.
Example 2: “Only one person in the world transmitted this hadith” is a far broader claim and demands a survey of all significant available routes.
The technical formulation “tafar rada bihi fulan ʿan fulan” usually points to a particular isolated link. If another route carries the same report independently, one must not elevate that local singularity into absolute singularity of the whole report.