What is the definition of a Shadh (anomalous) Hadith?

The anomalous (shādh) Hadith is one narrated by a trustworthy (thiqah) individual who contradicts other trustworthy narrators. This anomaly can be in the wording (lafẓ), the chain of transmission (sanad), or both. An example is the Hadith: "If a mouse falls into ghee." It is anomalous in its chain of transmission due to Ma'mar ibn Rashid's contradiction of other narrators in its isnad, and anomalous in its wording because its wording differs from the narrations of others, which do not include the distinction between solid and liquid ghee.